diff --git a/composer.json b/composer.json
index de7d184..c0b7ae4 100644
--- a/composer.json
+++ b/composer.json
@@ -11,9 +11,10 @@
     ],
     "minimum-stability": "stable",
     "require": {
-        "php": "^7.1|^8.0",
-        "nette/mail": "~3.0",
+        "php": "^8.1",
+        "nette/mail": "^3.1 || ^4.0",
         "nette/di": "^2.3 || ~3.0",
+        "doctrine/orm": "^2.9 || ^3.0",
         "tracy/tracy": "^2.3",
         "adt/background-queue": "^4.22"
     },
diff --git a/src/Entity/AbstractMailQueueEntry.php b/src/Entity/AbstractMailQueueEntry.php
index 82d7aa1..6274e61 100644
--- a/src/Entity/AbstractMailQueueEntry.php
+++ b/src/Entity/AbstractMailQueueEntry.php
@@ -6,38 +6,31 @@
 
 
 /**
- * @ORM\MappedSuperclass
+ * Mapping is defined as PHP attributes only - the annotation driver was removed
+ * in ORM 3, so projects using this package need the attribute driver.
+ *
  * @property \DateTime $createdAt
  * @property \DateTime|NULL $sentAt
  * @property string $from
  * @property string $subject
  * @property \Nette\Mail\Message|NULL $message
  */
+#[ORM\MappedSuperclass]
 abstract class AbstractMailQueueEntry {
 
-	/**
-	 * @ORM\Column(type="datetime")
-	 */
+	#[ORM\Column(type: 'datetime')]
 	protected $createdAt;
 
-	/**
-	 * @ORM\Column(type="datetime", nullable=true)
-	 */
+	#[ORM\Column(type: 'datetime', nullable: true)]
 	protected $sentAt;
 
-	/**
-	 * @ORM\Column(type="string", name="`from`")
-	 */
+	#[ORM\Column(type: 'string', name: '`from`')]
 	protected $from;
 
-	/**
-	 * @ORM\Column(type="text")
-	 */
+	#[ORM\Column(type: 'text')]
 	protected $subject;
 
-	/**
-	 * @ORM\Column(type="blob", nullable=true)
-	 */
+	#[ORM\Column(type: 'blob', nullable: true)]
 	protected $message;
 
 	/**
@@ -57,7 +50,7 @@ public function getMessage() {
 	 * @param \Nette\Mail\Message|NULL $message
 	 * @return $this
 	 */
-	public function setMessage(\Nette\Mail\Message $message = NULL): self {
+	public function setMessage(?\Nette\Mail\Message $message = NULL): self {
 		if ($message === NULL) {
 			$this->message = NULL;
 		} else {
diff --git a/src/Entity/MailQueueEntry.php b/src/Entity/MailQueueEntry.php
index 0a9efb3..c1e6455 100644
--- a/src/Entity/MailQueueEntry.php
+++ b/src/Entity/MailQueueEntry.php
@@ -5,9 +5,7 @@
 use Doctrine\ORM\Mapping as ORM;
 
 
-/**
- * @ORM\Entity
- */
+#[ORM\Entity]
 class MailQueueEntry extends AbstractMailQueueEntry {
 	use  \ADT\MailQueue\Traits\Identifier;
 }
diff --git a/src/Service/QueueMailer.php b/src/Service/QueueMailer.php
index 0bd9b8a..3471ace 100644
--- a/src/Service/QueueMailer.php
+++ b/src/Service/QueueMailer.php
@@ -2,7 +2,9 @@
 
 namespace ADT\MailQueue\Service;
 
-class QueueMailer implements \Nette\Mail\IMailer {
+// Nette\Mail\Mailer exists since nette/mail 3.1 (IMailer is its alias there)
+// and is the only name available in nette/mail 4, so it works for both generations.
+class QueueMailer implements \Nette\Mail\Mailer {
 
 	/** @var QueueService */
 	protected $queueService;
diff --git a/src/Service/QueueService.php b/src/Service/QueueService.php
index 60c6683..1c1549b 100644
--- a/src/Service/QueueService.php
+++ b/src/Service/QueueService.php
@@ -19,7 +19,7 @@ class QueueService {
 	/** @var string */
 	protected $queueEntryClass;
 
-	/** @var \Kdyby\Doctrine\EntityManager */
+	/** @var EntityManagerInterface */
 	protected $em;
 
 	/** @var string */
@@ -28,7 +28,7 @@ class QueueService {
 	/** @var string */
 	protected $mutexTimeFile;
 
-	/** @var \Nette\Mail\IMailer */
+	/** @var \Nette\Mail\Mailer */
 	protected $mailer;
 
 	/** @var IMessenger */
@@ -55,6 +55,9 @@ class QueueService {
 	/** @var string */
 	protected $backgroundQueueCallbackName;
 
+	/** @var bool|null Detected lazily via reflection - see flushEntry() */
+	protected $emSupportsSingleEntityFlush;
+
 	public function __construct($config, EntityManagerInterface $em) {
 		if (! is_dir($config['tempDir'])) {
 			mkdir($config['tempDir']);
@@ -73,7 +76,7 @@ public function __construct($config, EntityManagerInterface $em) {
 		$this->backgroundQueueCallbackName = $config['backgroundQueueCallbackName'];
 	}
 
-	public function setMailer(\Nette\Mail\IMailer $mailer) {
+	public function setMailer(\Nette\Mail\Mailer $mailer) {
 		$this->mailer = $mailer;
 		return $this;
 	}
@@ -122,7 +125,7 @@ protected function createQueueEntry(\Nette\Mail\Message $message, $custom = [])
 	public function enqueue(\Nette\Mail\Message $message, $custom = [], ?int $backgroundQueuePriority = null) {
 		$entry = $this->createQueueEntry($message, $custom);
 		$this->em->persist($entry);
-		$this->em->flush($entry);
+		$this->flushEntry($entry);
 
 		$this->backgroundQueueService->publish($this->backgroundQueueCallbackName, [$entry->getId()], null, null, false, null, $backgroundQueuePriority);
 
@@ -184,10 +187,29 @@ public function process(int $entryId) {
 		}
 
 		$this->em->persist($entry);
-		$this->em->flush($entry);
+		$this->flushEntry($entry);
 
 		return TRUE;
 	}
 
+	/**
+	 * Flushes the queue entry without touching other pending changes when possible.
+	 *
+	 * ORM 2 supports flushing a single entity, which keeps the caller's unit of work
+	 * untouched - enqueueing a mail must not write unrelated pending changes to DB.
+	 * ORM 3 removed single-entity flush, so there the full flush() is the only option
+	 * and callers should not enqueue mails with an unflushed unit of work.
+	 */
+	protected function flushEntry(Entity\AbstractMailQueueEntry $entry): void {
+		if ($this->emSupportsSingleEntityFlush === null) {
+			$this->emSupportsSingleEntityFlush = (new \ReflectionMethod($this->em, 'flush'))->getNumberOfParameters() > 0;
+		}
+
+		if ($this->emSupportsSingleEntityFlush) {
+			$this->em->flush($entry);
+		} else {
+			$this->em->flush();
+		}
+	}
 
 }
diff --git a/src/Traits/Identifier.php b/src/Traits/Identifier.php
index 654bce4..793ca70 100644
--- a/src/Traits/Identifier.php
+++ b/src/Traits/Identifier.php
@@ -2,15 +2,15 @@
 
 namespace ADT\MailQueue\Traits;
 
+use Doctrine\ORM\Mapping as ORM;
+
 
 trait Identifier
 {
-	/**
-	 * @ORM\Id
-	 * @ORM\Column(type="integer")
-	 * @ORM\GeneratedValue
-	 * @var integer|null
-	 */
+	/** @var integer|null */
+	#[ORM\Id]
+	#[ORM\Column(type: 'integer')]
+	#[ORM\GeneratedValue]
 	protected $id;
 
 	/**