diff --git a/CHANGES.md b/CHANGES.md
index 5d7b9b84..7e7ad9be 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -43,7 +43,7 @@ Note - All hash comments refer to the issue number. Eg. #169 refers to https://g
 
 ### Added
 
-- Only fetch teachers during the email process when necessary, reducing the number of SQL queries if they are not included (#531). 
+- Only fetch teachers during the email process when necessary, reducing the number of SQL queries if they are not included (#531).
 - Filter users before process to speed up certificate task (#634).
 
 ## [4.4.2] - 2024-09-28
@@ -62,7 +62,7 @@ Note - All hash comments refer to the issue number. Eg. #169 refers to https://g
 
 - Optimise email certificate task by reducing database reads/writes and introducing
   configurable settings for task efficiency (#531).
-- New element `expiry` which when used will display the expiry date on the list of issued certificates 
+- New element `expiry` which when used will display the expiry date on the list of issued certificates
   and the verification pages.<br />
   Any Custom Certificates that are using the `date` element and selected the expiry dates will
   automatically be upgraded to use this new element (#499).
@@ -144,7 +144,7 @@ Note - All hash comments refer to the issue number. Eg. #169 refers to https://g
   - An event for when a page is created.
   - An event for when a page is updated.
   - An event for when a page is deleted.
-  - An event for when a template is created. 
+  - An event for when a template is created.
   - An event for when a template is updated.
   - An event for when a template is deleted.
 
diff --git a/classes/task/email_certificate_task.php b/classes/task/email_certificate_task.php
index 92557fa8..0b904e10 100644
--- a/classes/task/email_certificate_task.php
+++ b/classes/task/email_certificate_task.php
@@ -53,6 +53,14 @@ public function execute() {
 
         $issueid = $customdata->issueid;
         $customcertid = $customdata->customcertid;
+
+        // Check if already emailed to prevent duplicates on retry.
+        $issue = $DB->get_record('customcert_issues', ['id' => $issueid], 'emailed');
+        if ($issue && $issue->emailed) {
+            mtrace("Certificate issue ID $issueid already emailed, skipping.");
+            return; // Already processed, skip to prevent duplicate emails.
+        }
+
         $sql = "SELECT c.*, ct.id as templateid, ct.name as templatename, ct.contextid, co.id as courseid,
                        co.fullname as coursefullname, co.shortname as courseshortname
                   FROM {customcert} c
@@ -62,6 +70,11 @@ public function execute() {
 
         $customcert = $DB->get_record_sql($sql, ['id' => $customcertid]);
 
+        if (!$customcert) {
+            mtrace("Certificate with ID $customcertid not found.");
+            return;
+        }
+
         // The renderers used for sending emails.
         $page = new \moodle_page();
         $htmlrenderer = $page->get_renderer('mod_customcert', 'email', 'htmlemail');
@@ -94,10 +107,15 @@ public function execute() {
                    AND ci.id = :issueid";
         $user = $DB->get_record_sql($sql, ['customcertid' => $customcertid, 'issueid' => $issueid]);
 
+        if (!$user) {
+            mtrace("User or certificate issue not found for issue ID $issueid.");
+            return;
+        }
+
         // Create a directory to store the PDF we will be sending.
         $tempdir = make_temp_directory('certificate/attachment');
         if (!$tempdir) {
-            return;
+            throw new \moodle_exception('Failed to create temporary directory for certificate attachment');
         }
 
         // Setup the user for the cron.
@@ -112,7 +130,15 @@ public function execute() {
         $template->name = $customcert->templatename;
         $template->contextid = $customcert->contextid;
         $template = new \mod_customcert\template($template);
-        $filecontents = $template->generate_pdf(false, $user->id, true);
+
+        try {
+            $filecontents = $template->generate_pdf(false, $user->id, true);
+        } catch (\Exception $e) {
+            // Log PDF generation failure and allow retry by throwing exception.
+            mtrace('Certificate PDF generation failed for issue ID ' . $issueid . ': ' . $e->getMessage());
+            debugging('Certificate PDF generation failed: ' . $e->getMessage(), DEBUG_DEVELOPER);
+            throw new \moodle_exception('PDF generation failed: ' . $e->getMessage());
+        }
 
         // Set the name of the file we are going to send.
         $filename = $courseshortname . '_' . $certificatename;
@@ -122,57 +148,144 @@ public function execute() {
         $filename = str_replace('&', '_', $filename) . '.pdf';
 
         // Create the file we will be sending.
-        $tempfile = $tempdir . '/' . md5(microtime() . $user->id) . '.pdf';
-        file_put_contents($tempfile, $filecontents);
+        $tempfile = $tempdir . '/' . md5(microtime() . $user->id . random_int(1000, 9999)) . '.pdf';
+        if (file_put_contents($tempfile, $filecontents) === false) {
+            mtrace('Certificate PDF could not be written to temp file for issue ID ' . $issueid);
+            debugging('Certificate PDF write failed for issue ID ' . $issueid, DEBUG_DEVELOPER);
+            throw new \moodle_exception('Failed to write PDF to temporary file');
+        }
+
+        $transaction = $DB->start_delegated_transaction();
+        try {
+            // Note: emailed flag is set before email sending.
+            // This is intentional to prevent infinite retries if emails fail.
+            $DB->set_field('customcert_issues', 'emailed', 1, ['id' => $issueid]);
+            mtrace("Marked certificate issue ID $issueid as emailed to prevent retries.");
 
+            // Track email sending results for logging
+            $emailresults = [];
+            $emailfailures = [];
+
+        // Now try to send emails; log any failures but DO NOT retry.
         if ($customcert->emailstudents) {
-            $renderable = new \mod_customcert\output\email_certificate(true, $userfullname, $courseshortname,
-                $coursefullname, $certificatename, $context->instanceid);
-
-            $subject = get_string('emailstudentsubject', 'customcert', $info);
-            $message = $textrenderer->render($renderable);
-            $messagehtml = $htmlrenderer->render($renderable);
-            email_to_user($user, $userfrom, html_entity_decode($subject, ENT_COMPAT), $message,
-                $messagehtml, $tempfile, $filename);
+            try {
+                $renderable = new \mod_customcert\output\email_certificate(
+                    true,
+                    $userfullname,
+                    $courseshortname,
+                    $coursefullname,
+                    $certificatename,
+                    $context->instanceid
+                );
+
+                $subject = get_string('emailstudentsubject', 'customcert', $info);
+                $message = $textrenderer->render($renderable);
+                $messagehtml = $htmlrenderer->render($renderable);
+
+                $result = email_to_user($user, $userfrom, html_entity_decode($subject, ENT_COMPAT), $message,
+                    $messagehtml, $tempfile, $filename);
+
+                if ($result) {
+                    $emailresults[] = "Student email sent to {$user->email}";
+                } else {
+                    $emailfailures[] = "Failed to send student email to {$user->email}";
+                }
+            } catch (\Exception $e) {
+                $emailfailures[] = "Exception sending student email: " . $e->getMessage();
+            }
         }
 
         if ($customcert->emailteachers) {
-            $teachers = get_enrolled_users($context, 'moodle/course:update');
+            try {
+                $teachers = get_enrolled_users($context, 'moodle/course:update');
 
-            $renderable = new \mod_customcert\output\email_certificate(false, $userfullname, $courseshortname,
-                $coursefullname, $certificatename, $context->instanceid);
+                $renderable = new \mod_customcert\output\email_certificate(false, $userfullname, $courseshortname,
+                    $coursefullname, $certificatename, $context->instanceid);
 
-            $subject = get_string('emailnonstudentsubject', 'customcert', $info);
-            $message = $textrenderer->render($renderable);
-            $messagehtml = $htmlrenderer->render($renderable);
-            foreach ($teachers as $teacher) {
-                email_to_user($teacher, $userfrom, html_entity_decode($subject, ENT_COMPAT),
-                    $message, $messagehtml, $tempfile, $filename);
+                $subject = get_string('emailnonstudentsubject', 'customcert', $info);
+                $message = $textrenderer->render($renderable);
+                $messagehtml = $htmlrenderer->render($renderable);
+
+                foreach ($teachers as $teacher) {
+                    try {
+                        $result = email_to_user($teacher, $userfrom, html_entity_decode($subject, ENT_COMPAT),
+                            $message, $messagehtml, $tempfile, $filename);
+
+                        if ($result) {
+                            $emailresults[] = "Teacher email sent to {$teacher->email}";
+                        } else {
+                            $emailfailures[] = "Failed to send teacher email to {$teacher->email}";
+                        }
+                    } catch (\Exception $e) {
+                        $emailfailures[] = "Exception sending teacher email to {$teacher->email}: " . $e->getMessage();
+                    }
+                }
+            } catch (\Exception $e) {
+                $emailfailures[] = "Exception getting teachers or sending teacher emails: " . $e->getMessage();
             }
         }
 
         if (!empty($customcert->emailothers)) {
-            $others = explode(',', $customcert->emailothers);
-            foreach ($others as $email) {
-                $email = trim($email);
-                if (validate_email($email)) {
-                    $renderable = new \mod_customcert\output\email_certificate(false, $userfullname,
-                        $courseshortname, $coursefullname, $certificatename, $context->instanceid);
+            try {
+                $others = explode(',', $customcert->emailothers);
+                $renderable = new \mod_customcert\output\email_certificate(false, $userfullname,
+    $courseshortname, $coursefullname, $certificatename, $context->instanceid);
 
                     $subject = get_string('emailnonstudentsubject', 'customcert', $info);
                     $message = $textrenderer->render($renderable);
                     $messagehtml = $htmlrenderer->render($renderable);
 
-                    $emailuser = new \stdClass();
-                    $emailuser->id = -1;
-                    $emailuser->email = $email;
-                    email_to_user($emailuser, $userfrom, html_entity_decode($subject, ENT_COMPAT), $message,
-                        $messagehtml, $tempfile, $filename);
+                    foreach ($others as $email) {
+                        $email = trim($email);
+                        if (validate_email($email)) {
+                            try {
+                            $emailuser = new \stdClass();
+                            $emailuser->id = -1;
+                            $emailuser->email = $email;
+
+                            $result = email_to_user($emailuser, $userfrom, html_entity_decode($subject, ENT_COMPAT), $message,
+                                $messagehtml, $tempfile, $filename);
+
+                            if ($result) {
+                                $emailresults[] = "Other email sent to {$email}";
+                            } else {
+                                $emailfailures[] = "Failed to send other email to {$email}";
+                            }
+                        } catch (\Exception $e) {
+                            $emailfailures[] = "Exception sending other email to {$email}: " . $e->getMessage();
+                        }
+                    } else {
+                        $emailfailures[] = "Invalid email address in others list: {$email}";
+                    }
                 }
+            } catch (\Exception $e) {
+                $emailfailures[] = "Exception processing other email addresses: " . $e->getMessage();
             }
         }
 
-        // Set the field so that it is emailed.
-        $DB->set_field('customcert_issues', 'emailed', 1, ['id' => $issueid]);
+        // Log results
+        if (!empty($emailresults)) {
+            mtrace("Email successes for issue ID $issueid: " . implode(', ', $emailresults));
+        }
+
+        if (!empty($emailfailures)) {
+            mtrace("Email failures for issue ID $issueid: " . implode(', ', $emailfailures));
+            debugging("Certificate email failures for issue ID $issueid: " . implode('; ', $emailfailures), DEBUG_DEVELOPER);
+        }
+
+        if (empty($emailresults)) {
+            throw new \moodle_exception("No emails sent successfully for issue ID $issueid; retrying later.");
+        }
+        $transaction->allow_commit();
+        // Clean up temporary file
+        if (file_exists($tempfile)) {
+            unlink($tempfile);
+        }
+        } catch (\Exception $e) {
+            $emailfailures[] = "Email sending failed: " . $e->getMessage();
+            $transaction->rollback($e);
+            throw $e;
+        }
+        mtrace("Certificate email task completed for issue ID $issueid.");
     }
 }
diff --git a/classes/template.php b/classes/template.php
index 870ffc44..d5645885 100644
--- a/classes/template.php
+++ b/classes/template.php
@@ -320,15 +320,23 @@ public function generate_pdf(bool $preview = false, ?int $userid = null, bool $r
             $pdf->SetAutoPageBreak(true, 0);
 
             // Get filename pattern from global settings.
-            if (empty($customcert->usecustomfilename) || empty($customcert->customfilenamepattern)) {
+            if (!empty($customcert->usecustomfilename) && !empty($customcert->customfilenamepattern)) {
+                $filenamepattern = $customcert->customfilenamepattern;
+            } else {
+                $filenamepattern = '{DEFAULT}';
+            }
+
+            if (empty($filenamepattern) || $filenamepattern === '{DEFAULT}') {
                 // Use the custom cert name as the base filename (strip any trailing dot).
                 $filename = rtrim(format_string($this->name, true, ['context' => $this->get_context()]), '.');
             } else {
+                // Build filename from pattern substitutions.
+
                 // Get issue record for date (if issued); fallback to current date if not found.
                 $issue = $DB->get_record('customcert_issues', [
                     'userid' => $user->id,
                     'customcertid' => $customcert->id,
-                ]);
+                ], '*', IGNORE_MISSING);
 
                 if ($issue && !empty($issue->timecreated)) {
                     $issuedate = date('Y-m-d', $issue->timecreated);
@@ -336,14 +344,14 @@ public function generate_pdf(bool $preview = false, ?int $userid = null, bool $r
                     $issuedate = date('Y-m-d');
                 }
 
-                $course = $DB->get_record('course', ['id' => $customcert->course]);
+                $course = $DB->get_record('course', ['id' => $customcert->course], '*', IGNORE_MISSING);
 
                 $values = [
-                    '{FIRST_NAME}' => $user->firstname ?? '',
-                    '{LAST_NAME}' => $user->lastname ?? '',
-                    '{COURSE_SHORT_NAME}' => $course ? $course->shortname : '',
-                    '{COURSE_FULL_NAME}' => $course ? $course->fullname : '',
-                    '{ISSUE_DATE}' => $issuedate,
+                    '{FIRST NAME}' => $user->firstname ?? '',
+                    '{LAST NAME}' => $user->lastname ?? '',
+                    '{COURSE SHORT NAME}' => $course ? $course->shortname : '',
+                    '{COURSE FULL NAME}' => $course ? $course->fullname : '',
+                    '{DATE}' => $issuedate,
                 ];
 
                 // Handle group if needed.
@@ -352,13 +360,13 @@ public function generate_pdf(bool $preview = false, ?int $userid = null, bool $r
                     $groupnames = array_map(function($g) {
                         return $g->name;
                     }, $groups);
-                    $values['{GROUP_NAME}'] = implode(', ', $groupnames);
+                    $values['{GROUP}'] = implode(', ', $groupnames);
                 } else {
-                    $values['{GROUP_NAME}'] = '';
+                    $values['{GROUP}'] = '';
                 }
 
                 // Replace placeholders with actual values.
-                $filename = strtr($customcert->customfilenamepattern, $values);
+                $filename = strtr($filenamepattern, $values);
 
                 // Remove trailing dot to avoid "..pdf" issues.
                 $filename = rtrim($filename, '.');
diff --git a/db/install.xml b/db/install.xml
index 9dff73d2..c685a809 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -59,7 +59,7 @@
       </KEYS>
       <INDEXES>
         <INDEX NAME="userid-customcertid" UNIQUE="false" FIELDS="userid, customcertid"/>
-        <INDEX NAME="code" UNIQUE="false" FIELDS="code"/>
+        <INDEX NAME="code" UNIQUE="true" FIELDS="code"/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="customcert_pages" COMMENT="Stores each page of a custom cert">
diff --git a/db/upgrade.php b/db/upgrade.php
index ad60bb29..e9ce8e7d 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -298,25 +298,27 @@ function xmldb_customcert_upgrade($oldversion) {
         upgrade_mod_savepoint(true, 2024042205, 'customcert');
     }
 
+    // Drop the unique index on 'code' and add a non-unique one.
     if ($oldversion < 2024042210) {
         $table = new xmldb_table('customcert_issues');
-        $index = new xmldb_index('code', XMLDB_INDEX_UNIQUE, ['code']);
 
+        // Drop existing unique index if it exists.
+        $index = new xmldb_index('code', XMLDB_INDEX_UNIQUE, ['code']);
         if ($dbman->index_exists($table, $index)) {
             $dbman->drop_index($table, $index);
         }
 
+        // Add non-unique index.
         $index = new xmldb_index('code', XMLDB_INDEX_NOTUNIQUE, ['code']);
-
         if (!$dbman->index_exists($table, $index)) {
             $dbman->add_index($table, $index);
         }
 
-        // Update the plugin version in the database.
+        // Save the upgrade step.
         upgrade_plugin_savepoint(true, 2024042210, 'mod', 'customcert');
     }
 
-    if ($oldversion < 2024042213) {
+    if ($oldversion < 2025062100) {
         $table = new xmldb_table('customcert');
 
         // Add 'usecustomfilename' field.
@@ -332,8 +334,7 @@ function xmldb_customcert_upgrade($oldversion) {
         }
 
         // Savepoint reached.
-        upgrade_mod_savepoint(true, 2024042213, 'customcert');
+        upgrade_mod_savepoint(true, 2025062100, 'customcert');
     }
-
     return true;
 }
diff --git a/element/qrcode/classes/element.php b/element/qrcode/classes/element.php
index 4cd88977..2a78e1b6 100644
--- a/element/qrcode/classes/element.php
+++ b/element/qrcode/classes/element.php
@@ -158,8 +158,7 @@ public function render($pdf, $preview, $user) {
             $context = \context::instance_by_id($issue->contextid);
 
             $urlparams = [
-                'code' => $code,
-                'qrcode' => 1,
+                'certId' => $code,
             ];
 
             // We only add the 'contextid' to the link if the site setting for verifying all certificates is off,
@@ -173,7 +172,7 @@ public function render($pdf, $preview, $user) {
                 $urlparams['contextid'] = $issue->contextid;
             }
 
-            $qrcodeurl = new \moodle_url('/mod/customcert/verify_certificate.php', $urlparams);
+            $qrcodeurl = new \moodle_url('https://app.pacificmedicaltraining.com/verify', $urlparams);
             $qrcodeurl = $qrcodeurl->out(false);
         }
 
diff --git a/lang/en/customcert.php b/lang/en/customcert.php
index 70108186..afc5bbf6 100644
--- a/lang/en/customcert.php
+++ b/lang/en/customcert.php
@@ -22,6 +22,7 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+$string['Upper/lower/digits'] = '6aOdbLEuoC (Upper/lower/digits random string)';
 $string['activity'] = 'Activity';
 $string['addcertpage'] = 'Add page';
 $string['addelement'] = 'Add element';
@@ -65,6 +66,8 @@
 $string['customcertsettings'] = 'Custom certificate settings';
 $string['customfilenamepattern'] = 'Custom file name pattern';
 $string['customfilenamepattern_help'] = 'Enter the pattern for naming certificate files. You can use placeholders such as {firstname}, {lastname}, {group}, {coursename}, {date}.';
+$string['custompattern'] = 'First name, Last name, Course short name, Issue date';
+$string['defaultpattern'] = 'Default (certificate name)';
 $string['deletecertpage'] = 'Delete page';
 $string['deleteconfirm'] = 'Delete confirmation';
 $string['deleteelement'] = 'Delete element';
@@ -73,10 +76,14 @@
 $string['deleteissuedcertificates'] = 'Delete issued certificates';
 $string['deletepageconfirm'] = 'Are you sure you want to delete this certificate page?';
 $string['deletetemplateconfirm'] = 'Are you sure you want to delete this certificate template?';
+$string['deliveryoption'] = 'Delivery option';
+$string['deliveryoption_help'] = 'Choose how the certificate should be delivered to users.';
 $string['deliveryoptiondownload'] = 'Send to the browser and force a file download';
 $string['deliveryoptioninline'] = 'Send the file inline to the browser';
 $string['deliveryoptions'] = 'Delivery options';
 $string['description'] = 'Description';
+$string['digits-with-hyphens'] = '0123-4567-8901 (Digits with hyphens)';
+$string['download'] = 'Force download';
 $string['downloadallissuedcertificates'] = 'Download all issued certificates';
 $string['downloadallsitecertificates'] = 'Download all site certificates';
 $string['downloadallsitecertificatesdesc'] = 'This will download all the certificates on the site in a zip file.';
@@ -125,6 +132,8 @@
 $string['eventtemplatedeleted'] = 'Custom certificate template deleted';
 $string['eventtemplateupdated'] = 'Custom certificate template updated';
 $string['exampledatawarning'] = 'Some of these values may just be an example to ensure positioning of the elements is possible.';
+$string['filenamepattern'] = 'File name pattern (legacy)';
+$string['filenamepattern_help'] = 'Choose the pattern for naming certificate files (legacy setting).';
 $string['font'] = 'Font';
 $string['font_help'] = 'The font used when generating this element.';
 $string['fontcolour'] = 'Colour';
@@ -137,6 +146,7 @@
 $string['height_help'] = 'This is the height of the certificate PDF in mm. For reference an A4 piece of paper is 297mm high and a letter is 279mm high.';
 $string['includeinnotvisiblecourses'] = 'Include certificates in hidden courses';
 $string['includeinnotvisiblecourses_desc'] = 'Certificates from hidden courses are not proccesed by default. If you want to include them, enable this setting.';
+$string['inline'] = 'Display inline';
 $string['invalidcode'] = 'Invalid code supplied.';
 $string['invalidcolour'] = 'Invalid colour chosen, please enter a valid HTML colour name, or a six-digit, or three-digit hexadecimal colour.';
 $string['invalidelementwidthorheightnotnumber'] = 'Please enter a valid number.';
@@ -241,7 +251,7 @@
 
 Enabling this option may improve the performance of the scheduled task by offloading email processing to ad-hoc tasks.';
 $string['usecustomfilename'] = 'Use custom file name pattern';
-$string['usecustomfilename_help'] = 'If enabled, you can define a custom file name pattern for certificates using placeholders. The placeholders are {FIRST_NAME}, {LAST_NAME}, {GROUP_NAME}, {COURSE_SHORT_NAME}, {COURSE_FULL_NAME} and {ISSUE_DATE}.';
+$string['usecustomfilename_help'] = 'If enabled, you can define a custom file name pattern for certificates using placeholders such as {FIRST NAME}, {LAST NAME}, {GROUP}, {COUSRE SHORT NAME}, {DATE}.';
 $string['userlanguage'] = 'Use user preferences';
 $string['userlanguage_help'] = 'You can force the language of the certificate to override the user\'s language preferences.';
 $string['verified'] = 'Verified';
diff --git a/lib.php b/lib.php
index 69afda51..959db7a2 100644
--- a/lib.php
+++ b/lib.php
@@ -436,6 +436,63 @@ function mod_customcert_inplace_editable($itemtype, $itemid, $newvalue) {
     }
 }
 
+// Prevent direct access to this file.
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Generates a public URL for viewing a user's certificate (eCard).
+ *
+ * This function constructs a URL that allows public access to a certificate
+ * without requiring authentication. It does so by generating a secure token
+ * based on the certificate code.
+ *
+ * @param string $cert_code The unique code of the certificate.
+ * @return string The generated public URL for the certificate.
+ */
+function generate_public_url_for_certificate(string $cert_code): string {
+    global $CFG;
+
+    // Generate a security token for the certificate using a private function.
+    $token = calculate_signature($cert_code);
+
+    // Construct and return the public URL to view the certificate.
+    return $CFG->wwwroot . '/mod/customcert/view_user_cert.php?cert_code=' . urlencode($cert_code) . '&token=' . urlencode($token);
+}
+
+/**
+ * Generates a secure HMAC signature for a certificate.
+ *
+ * This function creates a unique signature for a certificate based on its code.
+ * The signature is used as a security token to verify access to the certificate.
+ * It prevents unauthorized access by ensuring that only valid certificates can
+ * be accessed through a generated URL.
+ *
+ * The signature is generated using the HMAC (Hash-based Message Authentication Code)
+ * method with SHA-256, ensuring strong security. It uses Moodle's `siteidentifier`
+ * as the secret key, making it unique to each Moodle installation.
+ *
+ * @param string $cert_code The unique certificate code.
+ * @return string The generated HMAC signature.
+ */
+function calculate_signature(string $cert_code): string {
+    global $CFG;
+
+    // Define a namespaced message prefix to avoid signature collisions.
+    $messagePrefix = 'mod_customcert:view_user_cert';
+
+    // Construct the message that will be signed.
+    // This includes the prefix and the certificate code to create a unique hash.
+    $message = $messagePrefix . '|' . $cert_code;
+
+    // Use Moodle's unique site identifier as the secret key for HMAC.
+    // This ensures that signatures are installation-specific.
+    $secret = $CFG->siteidentifier;
+
+    // Generate the HMAC hash using SHA-256.
+    // This provides a cryptographic signature that is difficult to forge.
+    return hash_hmac('sha256', $message, $secret);
+}
+
 /**
  * Get icon mapping for font-awesome.
  */
diff --git a/mod_form.php b/mod_form.php
index 448fbba3..38382b96 100644
--- a/mod_form.php
+++ b/mod_form.php
@@ -77,6 +77,15 @@ public function definition() {
         $mform->addHelpButton('customfilenamepattern', 'customfilenamepattern', 'customcert');
         $mform->disabledIf('customfilenamepattern', 'usecustomfilename', 'notchecked');
 
+        if ($this->current) {
+            if (property_exists($this->current, 'usecustomfilename')) {
+                $mform->setDefault('usecustomfilename', $this->current->usecustomfilename);
+            }
+            if (property_exists($this->current, 'customfilenamepattern')) {
+                $mform->setDefault('customfilenamepattern', $this->current->customfilenamepattern);
+            }
+        }
+
         if (has_capability('mod/customcert:manageemailstudents', $this->get_context())) {
             $mform->addElement('selectyesno', 'emailstudents', get_string('emailstudents', 'customcert'));
             $mform->setDefault('emailstudents', get_config('customcert', 'emailstudents'));
diff --git a/tests/event/events_test.php b/tests/event/events_test.php
index 2636a7f6..1f1d9204 100644
--- a/tests/event/events_test.php
+++ b/tests/event/events_test.php
@@ -466,4 +466,87 @@ public function test_deleting_an_element(): void {
         $this->assertEquals($templateupdatedevent->contextid, \context_system::instance()->id);
         $this->assertDebuggingNotCalled();
     }
+    
+    /**
+     * Tests that the issue_created event is fired correctly.
+     */
+    public function test_issue_created_event(): void {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+        $user = $this->getDataGenerator()->create_user();
+        $customcert = $this->getDataGenerator()->create_module('customcert', ['course' => $course->id]);
+        $context = \context_module::instance($customcert->cmid);
+
+        // Simulate certificate issue.
+        $issue = new \stdClass();
+        $issue->userid = $user->id;
+        $issue->customcertid = $customcert->id;
+        $issue->timecreated = time();
+        $issueid = $DB->insert_record('customcert_issues', $issue);
+
+        $sink = $this->redirectEvents();
+
+        // Trigger event manually.
+        \mod_customcert\event\issue_created::create([
+            'objectid' => $issueid,
+            'context' => $context,
+            'relateduserid' => $user->id,
+            'userid' => $user->id,
+        ])->trigger();
+
+        $events = $sink->get_events();
+        $this->assertCount(1, $events);
+
+        $event = reset($events);
+        $this->assertInstanceOf(\mod_customcert\event\issue_created::class, $event);
+        $this->assertEquals($issueid, $event->objectid);
+        $this->assertEquals($context->id, $event->contextid);
+        $this->assertDebuggingNotCalled();
+    }
+
+    /**
+     * Tests that the issue_deleted event is fired correctly.
+     */
+    public function test_issue_deleted_event(): void {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        $course = $this->getDataGenerator()->create_course();
+        $user = $this->getDataGenerator()->create_user();
+        $customcert = $this->getDataGenerator()->create_module('customcert', ['course' => $course->id]);
+        $context = \context_module::instance($customcert->cmid);
+
+        // Create an issue.
+        $issue = new \stdClass();
+        $issue->userid = $user->id;
+        $issue->customcertid = $customcert->id;
+        $issue->timecreated = time();
+        $issueid = $DB->insert_record('customcert_issues', $issue);
+
+        $sink = $this->redirectEvents();
+
+        // Simulate deleting the issue.
+        $DB->delete_records('customcert_issues', ['id' => $issueid]);
+
+        // Trigger event manually.
+        \mod_customcert\event\issue_deleted::create([
+            'objectid' => $issueid,
+            'context' => $context,
+            'relateduserid' => $user->id,
+            'userid' => $user->id,
+        ])->trigger();
+
+        $events = $sink->get_events();
+        $this->assertCount(1, $events);
+
+        $event = reset($events);
+        $this->assertInstanceOf(\mod_customcert\event\issue_deleted::class, $event);
+        $this->assertEquals($issueid, $event->objectid);
+        $this->assertEquals($context->id, $event->contextid);
+        $this->assertDebuggingNotCalled();
+    }
 }
diff --git a/version.php b/version.php
index c4c7e3cd..1cb55de3 100644
--- a/version.php
+++ b/version.php
@@ -24,7 +24,7 @@
 
 defined('MOODLE_INTERNAL') || die('Direct access to this script is forbidden.');
 
-$plugin->version   = 2024042213; // The current module version (Date: YYYYMMDDXX).
+$plugin->version   = 2025062100; // The current module version (Date: YYYYMMDDXX).
 $plugin->requires  = 2024042200; // Requires this Moodle version (4.4).
 $plugin->cron      = 0; // Period for cron to check this module (secs).
 $plugin->component = 'mod_customcert';
diff --git a/view_user_cert.php b/view_user_cert.php
new file mode 100644
index 00000000..e71e1b77
--- /dev/null
+++ b/view_user_cert.php
@@ -0,0 +1,88 @@
+<?php
+// Include required Moodle configuration and custom certificate library.
+require_once(__DIR__ . '/../../config.php');
+require_once($CFG->dirroot . '/mod/customcert/lib.php');
+
+// Set up the page context before processing any parameters.
+// This ensures that Moodle properly initializes the page and handles any errors gracefully.
+$context = context_system::instance();
+$PAGE->set_context($context);
+$PAGE->set_url('/mod/customcert/view_user_cert.php');
+$PAGE->set_title('View certificate');
+$PAGE->set_heading('View certificate');
+
+/**
+ * Displays an error message in a formatted Moodle page and exits.
+ *
+ * This function helps standardize error handling by rendering the page
+ * properly and showing the error message in an alert box.
+ *
+ * @param string $message The error message to display.
+ */
+function display_error_page($message) {
+    global $OUTPUT;
+
+    echo $OUTPUT->header(); // Display the page header.
+    echo $OUTPUT->box($message, 'alert alert-danger'); // Display the error message in a styled box.
+    echo $OUTPUT->footer(); // Display the page footer.
+    exit; // Stop further execution.
+}
+
+// Retrieve certificate code and verification token from URL parameters.
+// 'optional_param' is used instead of 'required_param' to avoid Moodle throwing an automatic error page.
+$cert_code = optional_param('cert_code', '', PARAM_ALPHANUMEXT);
+$token = optional_param('token', '', PARAM_ALPHANUMEXT);
+
+// Ensure both required parameters are provided.
+if (empty($cert_code) || empty($token)) {
+    display_error_page('Certificate code or verification token is missing. Please check the URL and try again.');
+}
+
+// Validate the provided token by regenerating it using the expected algorithm.
+$expected_token = calculate_signature($cert_code);
+if ($token !== $expected_token) {
+    display_error_page('The verification token is invalid for this certificate. Please check the URL and try again.');
+}
+
+// Retrieve the certificate issue entry using the provided certificate code.
+// This helps fetch the associated user ID to verify ownership.
+$issue = $DB->get_record('customcert_issues', ['code' => $cert_code], '*');
+
+if (!$issue) {
+    display_error_page('The certificate with the provided code could not be found. Please verify the certificate code and try again.');
+}
+
+// Fetch the certificate associated with the retrieved issue.
+// The certificate must be one of the recognized eCard types: 'Cognitive eCard' or 'Completion eCard'.
+$certificate = $DB->get_record_sql("
+    SELECT * FROM {customcert}
+    WHERE id = ? AND name IN ('Cognitive eCard', 'Completion eCard')
+", [$issue->customcertid]);
+
+if (!$certificate) {
+    display_error_page('The certificate type is not valid or does not exist. Please contact the site administrator for assistance.');
+}
+
+// Retrieve the corresponding template for the fetched certificate.
+// The template defines the layout and content of the generated certificate.
+$template = $DB->get_record('customcert_templates', ['id' => $certificate->templateid]);
+if (!$template) {
+    display_error_page('The certificate template could not be found. Please contact the site administrator for assistance.');
+}
+
+try {
+    // Convert the template record into a template object.
+    // This object provides methods to generate and render the certificate.
+    $template = new \mod_customcert\template($template);
+
+    // Generate and output the certificate PDF.
+    // 'false' indicates that the PDF is displayed inline instead of being force-downloaded.
+    // The second parameter ensures the certificate is generated for the correct user.
+    $template->generate_pdf(false, $issue->userid);
+} catch (Exception $e) {
+    // Catch any errors that may occur while generating the certificate PDF.
+    display_error_page('There was an error generating the certificate PDF. Please try again later or contact support if the problem persists.');
+}
+
+// Prevent further execution after rendering the certificate.
+exit;