diff --git a/core/js/setupchecks.js b/core/js/setupchecks.js
index eae0abae50c..75d335043ac 100644
--- a/core/js/setupchecks.js
+++ b/core/js/setupchecks.js
@@ -293,6 +293,18 @@
 							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 						})
 					}
+					if (data.isPhpMailerUsed) {
+						messages.push({
+							msg: t(
+								'core',
+								'Use of the the built in php mailer is no longer supported. <a target="_blank" rel="noreferrer noopener" href="{docLink}">Please update your email server settings ↗<a/>.',
+								{
+									docLink: data.mailSettingsDocumentation,
+								}
+							),
+							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
+						});
+					}
 				} else {
 					messages.push({
 						msg: t('core', 'Error occurred while checking server setup'),
diff --git a/settings/Controller/CheckSetupController.php b/settings/Controller/CheckSetupController.php
index ecbb9839c75..a301ecb1f66 100644
--- a/settings/Controller/CheckSetupController.php
+++ b/settings/Controller/CheckSetupController.php
@@ -523,6 +523,10 @@ Raw output
 		return [];
 	}
 
+	protected function isPhpMailerUsed(): bool {
+		return $this->config->getSystemValue('mail_smtpmode', 'php') === 'php';
+	}
+
 	/**
 	 * @return DataResponse
 	 */
@@ -557,6 +561,8 @@ Raw output
 				'missingIndexes' => $this->hasMissingIndexes(),
 				'isSqliteUsed' => $this->isSqliteUsed(),
 				'databaseConversionDocumentation' => $this->urlGenerator->linkToDocs('admin-db-conversion'),
+				'isPhpMailerUsed' => $this->isPhpMailerUsed(),
+				'mailSettingsDocumentation' => $this->urlGenerator->getAbsoluteURL('index.php/settings/admin')
 			]
 		);
 	}
diff --git a/tests/Settings/Controller/CheckSetupControllerTest.php b/tests/Settings/Controller/CheckSetupControllerTest.php
index 470bc9cde64..057774a45ba 100644
--- a/tests/Settings/Controller/CheckSetupControllerTest.php
+++ b/tests/Settings/Controller/CheckSetupControllerTest.php
@@ -119,7 +119,22 @@ class CheckSetupControllerTest extends TestCase {
 				$this->lockingProvider,
 				$this->dateTimeFormatter,
 				])
-			->setMethods(['isReadOnlyConfig', 'hasValidTransactionIsolationLevel', 'hasFileinfoInstalled', 'hasWorkingFileLocking', 'getLastCronInfo', 'getSuggestedOverwriteCliURL', 'getOutdatedCaches', 'getCurlVersion', 'isPhpOutdated', 'isOpcacheProperlySetup', 'hasFreeTypeSupport', 'hasMissingIndexes', 'isSqliteUsed'])->getMock();
+			->setMethods([
+				'isReadOnlyConfig',
+				'hasValidTransactionIsolationLevel',
+				'hasFileinfoInstalled',
+				'hasWorkingFileLocking',
+				'getLastCronInfo',
+				'getSuggestedOverwriteCliURL',
+				'getOutdatedCaches',
+				'getCurlVersion',
+				'isPhpOutdated',
+				'isOpcacheProperlySetup',
+				'hasFreeTypeSupport',
+				'hasMissingIndexes',
+				'isSqliteUsed',
+				'isPhpMailerUsed',
+			])->getMock();
 	}
 
 	public function testIsInternetConnectionWorkingDisabledViaConfig() {
@@ -352,6 +367,10 @@ class CheckSetupControllerTest extends TestCase {
 			->method('linkToDocs')
 			->with('admin-db-conversion')
 			->willReturn('http://docs.example.org/server/go.php?to=admin-db-conversion');
+		$this->urlGenerator->expects($this->at(6))
+			->method('getAbsoluteURL')
+			->with('index.php/settings/admin')
+			->willReturn('https://server/index.php/settings/admin');
 		$this->checkSetupController
 			->method('hasFreeTypeSupport')
 			->willReturn(false);
@@ -392,6 +411,10 @@ class CheckSetupControllerTest extends TestCase {
 				'relativeTime' => '2 hours ago',
 				'backgroundJobsUrl' => 'https://example.org',
 			]);
+		$this->checkSetupController
+			->expects($this->once())
+			->method('isPhpMailerUsed')
+			->willReturn(false);
 		$this->checker
 			->expects($this->once())
 			->method('hasPassedCheck')
@@ -434,6 +457,8 @@ class CheckSetupControllerTest extends TestCase {
 				'isSqliteUsed' => false,
 				'databaseConversionDocumentation' => 'http://docs.example.org/server/go.php?to=admin-db-conversion',
 				'missingIndexes' => [],
+				'isPhpMailerUsed' => false,
+				'mailSettingsDocumentation' => 'https://server/index.php/settings/admin',
 			]
 		);
 		$this->assertEquals($expected, $this->checkSetupController->check());