diff --git a/src/Folder.php b/src/Folder.php
index bd30cc2..1b72e66 100644
--- a/src/Folder.php
+++ b/src/Folder.php
@@ -2,6 +2,7 @@
 
 namespace DirectoryTree\ImapEngine;
 
+use Closure;
 use DirectoryTree\ImapEngine\Connection\ImapQueryBuilder;
 use DirectoryTree\ImapEngine\Connection\Responses\UntaggedResponse;
 use DirectoryTree\ImapEngine\Enums\ImapFetchIdentifier;
@@ -92,12 +93,17 @@ public function messages(): MessageQuery
     /**
      * {@inheritDoc}
      */
-    public function idle(callable $callback, ?callable $query = null, int $timeout = 300): void
+    public function idle(callable $callback, ?callable $query = null, callable|int $timeout = 300): void
     {
         if (! in_array('IDLE', $this->mailbox->capabilities())) {
             throw new ImapCapabilityException('Unable to IDLE. IMAP server does not support IDLE capability.');
         }
 
+        // Normalize timeout into a closure.
+        if (is_callable($timeout) && ! $timeout instanceof Closure) {
+            $timeout = $timeout(...);
+        }
+
         // The message query to use when fetching messages.
         $query ??= fn (MessageQuery $query) => $query;
 
diff --git a/src/FolderInterface.php b/src/FolderInterface.php
index d6a5910..e0d1102 100644
--- a/src/FolderInterface.php
+++ b/src/FolderInterface.php
@@ -44,7 +44,7 @@ public function messages(): MessageQueryInterface;
     /**
      * Begin idling on the current folder.
      */
-    public function idle(callable $callback, ?callable $query = null, int $timeout = 300): void;
+    public function idle(callable $callback, ?callable $query = null, callable|int $timeout = 300): void;
 
     /**
      * Move or rename the current folder.
diff --git a/src/Idle.php b/src/Idle.php
index ed45659..60f8a9c 100644
--- a/src/Idle.php
+++ b/src/Idle.php
@@ -4,6 +4,7 @@
 
 use Carbon\Carbon;
 use Carbon\CarbonInterface;
+use Closure;
 use DirectoryTree\ImapEngine\Connection\Responses\UntaggedResponse;
 use DirectoryTree\ImapEngine\Exceptions\Exception;
 use DirectoryTree\ImapEngine\Exceptions\ImapConnectionClosedException;
@@ -18,7 +19,7 @@ class Idle
     public function __construct(
         protected Mailbox $mailbox,
         protected string $folder,
-        protected int $timeout,
+        protected Closure|int $timeout,
     ) {}
 
     /**
@@ -36,10 +37,7 @@ public function await(callable $callback): void
     {
         $this->connect();
 
-        // Loop indefinitely, restarting IDLE sessions as needed.
-        while (true) {
-            $ttl = $this->getNextTimeout();
-
+        while ($ttl = $this->getNextTimeout()) {
             try {
                 $this->listen($callback, $ttl);
             } catch (ImapConnectionTimedOutException) {
@@ -56,7 +54,7 @@ public function await(callable $callback): void
     protected function listen(callable $callback, CarbonInterface $ttl): void
     {
         // Iterate over responses yielded by the idle generator.
-        foreach ($this->idle() as $response) {
+        foreach ($this->idle($ttl) as $response) {
             if (! $response instanceof UntaggedResponse) {
                 continue;
             }
@@ -69,6 +67,10 @@ protected function listen(callable $callback, CarbonInterface $ttl): void
                 $ttl = $this->getNextTimeout();
             }
 
+            if ($ttl === false) {
+                break;
+            }
+
             // If we've been idle too long, break out to restart the session.
             if (Carbon::now()->greaterThanOrEqualTo($ttl)) {
                 $this->restart();
@@ -145,16 +147,22 @@ protected function done(): void
     /**
      * Begin a new IDLE session as a generator.
      */
-    protected function idle(): Generator
+    protected function idle(CarbonInterface $ttl): Generator
     {
-        yield from $this->mailbox->connection()->idle($this->timeout);
+        yield from $this->mailbox->connection()->idle(
+            (int) Carbon::now()->diffInSeconds($ttl, true)
+        );
     }
 
     /**
      * Get the next timeout as a Carbon instance.
      */
-    protected function getNextTimeout(): CarbonInterface
+    protected function getNextTimeout(): CarbonInterface|false
     {
-        return Carbon::now()->addSeconds($this->timeout);
+        if (is_numeric($seconds = value($this->timeout))) {
+            return Carbon::now()->addSeconds(abs($seconds));
+        }
+
+        return false;
     }
 }
diff --git a/src/Testing/FakeFolder.php b/src/Testing/FakeFolder.php
index aafb8a8..d2c6116 100644
--- a/src/Testing/FakeFolder.php
+++ b/src/Testing/FakeFolder.php
@@ -89,7 +89,7 @@ public function messages(): MessageQueryInterface
     /**
      * {@inheritDoc}
      */
-    public function idle(callable $callback, ?callable $query = null, int $timeout = 300): void
+    public function idle(callable $callback, ?callable $query = null, callable|int $timeout = 300): void
     {
         foreach ($this->messages as $message) {
             $callback($message);