diff --git a/lib/Cache/Cache.php b/lib/Cache/Cache.php
index fc1cbc8c5c..ea49e80990 100644
--- a/lib/Cache/Cache.php
+++ b/lib/Cache/Cache.php
@@ -230,7 +230,7 @@ public function getMetaData($mailbox, $uidvalid, $entries) {
 	 * @return void
 	 */
 	public function setMetaData($mailbox, $data) {
-		$this->_loadSliceMap($mailbox, isset($data['uidvalid']) ? $data['uidvalid'] : null);
+		$this->_loadSliceMap($mailbox, $data['uidvalid'] ?? null);
 		$this->_slicemap[$mailbox]['d'] = array_merge($this->_slicemap[$mailbox]['d'], $data);
 		$this->_toUpdate($mailbox, 'slicemap', true);
 	}
diff --git a/lib/Command/ExportAccount.php b/lib/Command/ExportAccount.php
index 0b9e74949d..6039dbaf3e 100644
--- a/lib/Command/ExportAccount.php
+++ b/lib/Command/ExportAccount.php
@@ -83,7 +83,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 				$output->writeln('<info>Account ' . $account->getId() . ':</info>');
 				$output->writeln('- E-Mail: ' . $account->getEmail());
 				$output->writeln('- Name: ' . $account->getName());
-				$output->writeln('- Provision: ' . ($account->getMailAccount()->getProvisioningId() ? 'set' : 'none'). ' ID: ' . ($account->getMailAccount()->getProvisioningId() ? $account->getMailAccount()->getProvisioningId():'N/A'));
+				$output->writeln('- Provision: ' . ($account->getMailAccount()->getProvisioningId() ? 'set' : 'none'). ' ID: ' . ($account->getMailAccount()->getProvisioningId() ?: 'N/A'));
 				$output->writeln('- IMAP user: ' . $account->getMailAccount()->getInboundUser());
 				$output->writeln('- IMAP host: ' . $account->getMailAccount()->getInboundHost() . ':' . $account->getMailAccount()->getInboundPort() . ', security: ' . $account->getMailAccount()->getInboundSslMode());
 				$output->writeln('- SMTP user: ' . $account->getMailAccount()->getOutboundUser());
diff --git a/lib/Service/AiIntegrations/Cache.php b/lib/Service/AiIntegrations/Cache.php
index 1d9d6775f2..c4905f61b9 100644
--- a/lib/Service/AiIntegrations/Cache.php
+++ b/lib/Service/AiIntegrations/Cache.php
@@ -55,7 +55,7 @@ public function getValue(string $key) {
 	 * @return void
 	 */
 	public function addValue(string $key, ?string $value): void {
-		$this->cache->set($key, $value === null ? false : $value, self::CACHE_TTL);
+		$this->cache->set($key, $value ?? false, self::CACHE_TTL);
 	}
 
 
diff --git a/lib/Service/Attachment/UploadedFile.php b/lib/Service/Attachment/UploadedFile.php
index 7a1d88eaf5..f31bb6334b 100644
--- a/lib/Service/Attachment/UploadedFile.php
+++ b/lib/Service/Attachment/UploadedFile.php
@@ -24,20 +24,20 @@ public function __construct(array $fileData) {
 	 * @return string|null
 	 */
 	public function getFileName() {
-		return isset($this->fileData['name']) ? $this->fileData['name'] : null;
+		return $this->fileData['name'] ?? null;
 	}
 
 	/**
 	 * @return string|null
 	 */
 	public function getTempPath() {
-		return isset($this->fileData['tmp_name']) ? $this->fileData['tmp_name'] : null;
+		return $this->fileData['tmp_name'] ?? null;
 	}
 
 	/**
 	 * @return string
 	 */
 	public function getMimeType() {
-		return isset($this->fileData['type']) ? $this->fileData['type'] : 'application/octet-stream';
+		return $this->fileData['type'] ?? 'application/octet-stream';
 	}
 }
diff --git a/rector.php b/rector.php
index 433aac517a..aec92a3cd6 100644
--- a/rector.php
+++ b/rector.php
@@ -20,4 +20,7 @@
 	->withPreparedSets(
 		phpunitCodeQuality: true,
 		phpunit: true,
+	)
+	->withPhpSets(
+		php73: true,
 	);
diff --git a/tests/Integration/Db/CollectedAddressMapperTest.php b/tests/Integration/Db/CollectedAddressMapperTest.php
index 3b1a915652..76ebd09a9b 100644
--- a/tests/Integration/Db/CollectedAddressMapperTest.php
+++ b/tests/Integration/Db/CollectedAddressMapperTest.php
@@ -104,7 +104,7 @@ public function testFindMatching($query, $result) {
 		$this->assertCount(\count($result), $matches);
 		$i = 0;
 		foreach ($matches as $match) {
-			$this->assertInstanceOf('\OCA\Mail\Db\CollectedAddress', $match);
+			$this->assertInstanceOf(\OCA\Mail\Db\CollectedAddress::class, $match);
 			$this->assertContains($match->getEmail(), $result);
 			$this->assertEquals($this->userId, $match->getUserId());
 			$i++;
diff --git a/tests/Integration/Db/RecipientMapperTest.php b/tests/Integration/Db/RecipientMapperTest.php
index 96b3d73119..3422621e25 100644
--- a/tests/Integration/Db/RecipientMapperTest.php
+++ b/tests/Integration/Db/RecipientMapperTest.php
@@ -172,7 +172,7 @@ public function testUpdateRecipients(): void {
 		$penny->setEmail('penny@stardewvalleylibrary.edu');
 		$penny->setLabel('Penny');
 		$penny->setType(Recipient::TYPE_TO);
-		$this->mapper->saveRecipients($message->getId(), [$penny], Recipient::TYPE_BCC);
+		$this->mapper->saveRecipients($message->getId(), [$penny]);
 
 		$results = $this->mapper->findByLocalMessageId($message->getId());
 		$this->assertCount(1, $results);
diff --git a/tests/Integration/Service/MailTransmissionIntegrationTest.php b/tests/Integration/Service/MailTransmissionIntegrationTest.php
index 2f23543851..66653c1565 100644
--- a/tests/Integration/Service/MailTransmissionIntegrationTest.php
+++ b/tests/Integration/Service/MailTransmissionIntegrationTest.php
@@ -151,7 +151,7 @@ public function testSendMail() {
 	public function testSendMailWithLocalAttachment() {
 		$file = new UploadedFile([
 			'name' => 'text.txt',
-			'tmp_name' => dirname(__FILE__) . '/../../data/mail-message-123.txt',
+			'tmp_name' => __DIR__ . '/../../data/mail-message-123.txt',
 		]);
 
 		$localAttachment = $this->attachmentService->addFile($this->user->getUID(), $file);
diff --git a/tests/Unit/Command/CreateAccountTest.php b/tests/Unit/Command/CreateAccountTest.php
index d43b7d6f88..e95aba3399 100644
--- a/tests/Unit/Command/CreateAccountTest.php
+++ b/tests/Unit/Command/CreateAccountTest.php
@@ -41,7 +41,7 @@ class CreateAccountTest extends TestCase {
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->service = $this->getMockBuilder('\OCA\Mail\Service\AccountService')
+		$this->service = $this->getMockBuilder(\OCA\Mail\Service\AccountService::class)
 			->disableOriginalConstructor()
 			->getMock();
 		$this->crypto = $this->getMockBuilder('\OCP\Security\ICrypto')->getMock();
diff --git a/tests/Unit/Controller/AliasesControllerTest.php b/tests/Unit/Controller/AliasesControllerTest.php
index 9c75f01353..51e36e7933 100644
--- a/tests/Unit/Controller/AliasesControllerTest.php
+++ b/tests/Unit/Controller/AliasesControllerTest.php
@@ -40,7 +40,7 @@ public function setUp(): void {
 		$this->request = $this->getMockBuilder('OCP\IRequest')
 			->getMock();
 
-		$this->alias = $this->getMockBuilder('\OCA\Mail\Db\Alias')
+		$this->alias = $this->getMockBuilder(\OCA\Mail\Db\Alias::class)
 			->disableOriginalConstructor()
 			->getMock();
 
diff --git a/tests/Unit/Controller/AutoCompleteControllerTest.php b/tests/Unit/Controller/AutoCompleteControllerTest.php
index 960b1fcdb0..ed60301f1d 100644
--- a/tests/Unit/Controller/AutoCompleteControllerTest.php
+++ b/tests/Unit/Controller/AutoCompleteControllerTest.php
@@ -21,7 +21,7 @@ protected function setUp(): void {
 		parent::setUp();
 
 		$this->request = $this->getMockBuilder('OCP\IRequest')->getMock();
-		$this->service = $this->getMockBuilder('OCA\Mail\Service\AutoCompletion\AutoCompleteService')
+		$this->service = $this->getMockBuilder(\OCA\Mail\Service\AutoCompletion\AutoCompleteService::class)
 			->disableOriginalConstructor()
 			->getMock();
 		$this->controller = new AutoCompleteController(
diff --git a/tests/Unit/Http/AttachmentDownloadResponseTest.php b/tests/Unit/Http/AttachmentDownloadResponseTest.php
index bcdd441e6f..f63ef75886 100644
--- a/tests/Unit/Http/AttachmentDownloadResponseTest.php
+++ b/tests/Unit/Http/AttachmentDownloadResponseTest.php
@@ -14,11 +14,8 @@
 class AttachmentDownloadResponseTest extends TestCase {
 	/**
 	 * @dataProvider providesResponseData
-	 * @param $content
-	 * @param $filename
-	 * @param $contentType
 	 */
-	public function testIt($content, $filename, $contentType) {
+	public function testIt(string $content, string $filename, string $contentType) {
 		$resp = new AttachmentDownloadResponse($content, $filename, $contentType);
 		$headers = $resp->getHeaders();
 		$this->assertEquals($content, $resp->render());
diff --git a/tests/Unit/Http/ProxyDownloadResponseTest.php b/tests/Unit/Http/ProxyDownloadResponseTest.php
index 42668596c9..a24d3c403d 100644
--- a/tests/Unit/Http/ProxyDownloadResponseTest.php
+++ b/tests/Unit/Http/ProxyDownloadResponseTest.php
@@ -25,7 +25,7 @@ public function testIt($content, $filename, $contentType) {
 		$this->assertArrayHasKey('Content-Type', $headers);
 		$this->assertEquals($contentType, $headers['Content-Type']);
 		$this->assertArrayHasKey('Content-Disposition', $headers);
-		$pos = strpos($headers['Content-Disposition'], $filename);
+		$pos = strpos($headers['Content-Disposition'], (string)$filename);
 		$this->assertTrue($pos > 0);
 	}