Refactor EMailSender to improve chunk encoding and sending for string content; update OpenSLab SSL client enablement instructions #55 #54

Author: xreef

README.md

@@ -1,4 +1,4 @@
-# EMailSender Library v4.1.0
+# EMailSender Library v4.1.1
 
 ![EMailSender Logo](https://raw.githubusercontent.com/xreef/EMailSender/master/resources/EMailSenderLogo.jpg)
 
@@ -155,7 +155,7 @@ Complete tutorials and articles available on [mischianti.org](https://www.mischi
 Add to your `platformio.ini`:
 ```ini
 lib_deps = 
-    xreef/EMailSender@^4.1.0
+    xreef/EMailSender@^4.1.1
 ```
 
 ### Manual Installation
@@ -275,6 +275,9 @@ For boards with limited RAM (like Arduino Uno):
 - Regular account password will not work
 
 ## Change log v4.x
+- 10/11/2025: v4.1.1
+  - Minor enhancements: add support for Stream and String attachments improvements
+  - Bug fixes: edge-case encoding issues and small fixes in attachment handling
 - 10/11/2025: v4.1.0
   - Add Stream and File as attachement type
   - Bug fix for size and encoding

library.json

@@ -16,6 +16,6 @@
 	},
 	"url": "https://www.mischianti.org/category/my-libraries/emailsender-send-email-with-attachments/",
 	"frameworks": "Arduino",
-    "version": "4.1.0",
+    "version": "4.1.1",
 	"platforms": "*"
 }

library.properties

@@ -1,5 +1,5 @@
 name=EMailSender
-version=4.1.0
+version=4.1.1
 author=Renzo Mischianti <renzo.mischianti@gmail.com>
 maintainer=Renzo Mischianti <renzo.mischianti@gmail.com>
 sentence=Send EMail via SMTP with STARTTLS support, library for Raspberry Pi Pico W, Arduino, SAMD (WiFiNINA), STM32, esp8266 and esp32.

src/EMailSender.cpp

@@ -1238,14 +1238,16 @@ EMailSender::Response EMailSender::send(const char* to[], byte sizeOfTo,  byte s
 						tBuf[j] = stringContent.charAt(pos + j);
 					}
 					// Encode and send chunk
-					client.write(encode64((byte*)tBuf, chunkSize).c_str());
+					const char* encoded = encode64_f((char*)tBuf, chunkSize);
+					client.print(encoded);
 				}
 			} else {
 				EMAIL_SENDER_DEBUG_PRINTLN(F("NORMAL write from String"));
 				// Send string content directly in chunks
 				for (size_t pos = 0; pos < totalSize; pos += 512) {
 					size_t chunkSize = min((size_t)512, totalSize - pos);
-					client.write(stringContent.substring(pos, pos + chunkSize).c_str());
+					String chunk = stringContent.substring(pos, pos + chunkSize);
+					client.print(chunk);
 				}
 			}
 

src/EMailSender.h

@@ -2,7 +2,7 @@
  * EMail Sender Arduino, esp8266, stm32 and esp32 library to send email
  *
  * AUTHOR:  Renzo Mischianti
- * VERSION: 4.1.0
+ * VERSION: 4.1.1
  *
  * https://www.mischianti.org/
  *

src/EMailSenderKey.h

@@ -2,7 +2,7 @@
  * EMail Sender Arduino, esp8266, stm32 and esp32 library to send email
  *
  * AUTHOR:  Renzo Mischianti
- * VERSION: 4.1.0
+ * VERSION: 4.1.1
  *
  * https://www.mischianti.org/
  *

src/EMailSender_OpenSLabUnity.cpp

@@ -9,7 +9,10 @@
  *  This is necessary because the Arduino IDE has limitations on how it discovers and compiles source files in subdirectories.
  */
 
-#define EMAIL_ENABLE_OPENSLAB_SSLCLIENT
+// NOTE: Do NOT force-enable EMAIL_ENABLE_OPENSLAB_SSLCLIENT here.
+// The feature should be enabled explicitly in EMailSenderKey.h or via build flags
+// (for example -DEMAIL_ENABLE_OPENSLAB_SSLCLIENT) so users control whether
+// the OpenSLab SSL client backend is compiled.
 
 #if defined(EMAIL_ENABLE_OPENSLAB_SSLCLIENT) && !defined(EMAIL_ENABLE_EXTERNAL_SSLCLIENT_OPENSLAB)