diff --git a/README.md b/README.md
index 82f8da7..c9e63b5 100644
--- a/README.md
+++ b/README.md
@@ -20,15 +20,20 @@ extensions:
 adtMailer:
 	remote:
 		api: yourAdtMailApiInstance.com:1234
+
+		# can be either static string or method, required
 		key: yourPrivateKey
+
 	error:
 		# mode: silent => log and continue
 		# mode: exception => throw 
 		mode: silent
+
 		# all undelivered messages are stored here (applies to mode: silent)
 		logDir: %logDir%/adt_mailer
+
 	# if recipient is suppressed, this address receives notification and delist link
-	# can be either static string or method, required
+	# can be either an email address, url or a callback returning an email address or url
 	suppressionControlAddress: @App\Model\SuppressionControl::decide
 ```
 
diff --git a/composer.json b/composer.json
index bd69fdb..8219025 100644
--- a/composer.json
+++ b/composer.json
@@ -11,11 +11,11 @@
     ],
     "minimum-stability": "stable",
     "require": {
-        "php": ">=7.1",
-        "nette/mail": "~3.0",
+        "php": ">=7.4",
+        "nette/mail": "^2.3 | ^3.0 | ^4.0",
         "tracy/tracy": "^2.3",
-        "nette/di": "~3.0",
-        "guzzlehttp/guzzle": "^6.3"
+        "nette/di": "^2.3 || ^3.0",
+        "guzzlehttp/guzzle": "^6.3|^7.0"
     },
     "require-dev": {
     },
diff --git a/src/DI/AdtMailerExtension.php b/src/DI/AdtMailerExtension.php
index b23205f..d9d3af7 100644
--- a/src/DI/AdtMailerExtension.php
+++ b/src/DI/AdtMailerExtension.php
@@ -44,15 +44,15 @@ public function loadConfiguration() {
 			->setAutowired($config['autowireMailer']);
 	}
 
-	public function validateConfig(array $expected, array $config = NULL, $name = NULL): array {
+	public function validateConfig(array $expected, ?array $config = NULL, $name = NULL): array {
 		$config = parent::validateConfig($expected, $config, $name);
 
 		if (empty($config['remote']['api'])) {
 			throw new \Nette\UnexpectedValueException('Specify remote API endpoint.');
 		}
 
-		if (empty($config['remote']['key'])) {
-			throw new \Nette\UnexpectedValueException('Specify authentication key.');
+		if (empty($config['remote']['key']) || !(is_string($config['remote']['key']) || is_array($config['remote']['key']))) {
+			throw new \Nette\UnexpectedValueException('Specify authentication key as string or method (e.g. [@ServiceClass, method]).');
 		}
 
 		if (!in_array($config['error']['mode'], static::errorModes(), TRUE)) {
@@ -65,12 +65,7 @@ public function validateConfig(array $expected, array $config = NULL, $name = NU
 			throw new \Nette\UnexpectedValueException('Specify mail log directory.');
 		}
 
-		if (empty($config['suppressionControlAddress']) || !(is_string($config['suppressionControlAddress']) || is_callable(array_map(function($value) { return ltrim($value, '@'); }, $config['suppressionControlAddress'])))) {
-			throw new \Nette\UnexpectedValueException('Specify suppression control address as string or method (e.g. @ServiceClass::method).');
-		}
-
 		return $config;
 	}
 
-
 }
diff --git a/src/Services/Api.php b/src/Services/Api.php
index e7d4bea..ce748de 100644
--- a/src/Services/Api.php
+++ b/src/Services/Api.php
@@ -19,12 +19,18 @@ public function __construct(array $config, \Tracy\ILogger $logger) {
 	}
 
 	protected function getSuppressionControlAddress(\Nette\Mail\Message $mail) {
-		$address = $this->config['suppressionControlAddress'];
+		return $this->processCallableOption($this->config['suppressionControlAddress'], $mail);
+	}
+
+	protected function getRemoteKey(\Nette\Mail\Message $mail) {
+		return $this->processCallableOption($this->config['remote']['key'], $mail);
+	}
 
-		if (is_callable($address, FALSE)) {
-			return $address($mail);
+	protected function processCallableOption($value, \Nette\Mail\Message $mail) {
+		if (is_callable($value, FALSE)) {
+			return $value($mail);
 		} else {
-			return $address;
+			return $value;
 		}
 	}
 
@@ -44,6 +50,10 @@ protected function serializeMessage(\Nette\Mail\Message $mail) {
 			$result[$header] = $mail->getHeader(ucfirst($header));
 		}
 
+		if ($mail->getHeader('Reply-To') !== null) {
+			$result['reply-to'] = $mail->getHeader('Reply-To');
+		}
+
 		return $result;
 	}
 
@@ -60,7 +70,7 @@ public function send(\Nette\Mail\Message $mail) {
 		$client = new Client;
 
 		try {
-			$client->request("POST", $endPoint . '/mail/send?key=' . $this->config['remote']['key'], [
+			$client->request("POST", $endPoint . '/mail/send?key=' . $this->getRemoteKey($mail), [
 				'headers' => [
 					'Cache-Control'=> 'no-cache',
 					'Content-Type' => 'application/octet-stream',
@@ -100,4 +110,4 @@ public function send(\Nette\Mail\Message $mail) {
 }
 
 class ApiException extends \Nette\IOException {
-}
\ No newline at end of file
+}
diff --git a/src/Services/Mailer.php b/src/Services/Mailer.php
index ffcb4e7..c2d0459 100644
--- a/src/Services/Mailer.php
+++ b/src/Services/Mailer.php
@@ -17,4 +17,4 @@ function send(Message $mail): void {
 		$this->apiService->send($mail);
 	}
 
-}
\ No newline at end of file
+}