diff --git a/lib/Service/MailManager.php b/lib/Service/MailManager.php
index 1fb1ce58fa..bb8ad80c4f 100644
--- a/lib/Service/MailManager.php
+++ b/lib/Service/MailManager.php
@@ -759,11 +759,12 @@ public function isPermflagsEnabled(Horde_Imap_Client_Socket $client, Account $ac
 		try {
 			$capabilities = $client->status($mailbox, Horde_Imap_Client::STATUS_PERMFLAGS);
 		} catch (Horde_Imap_Client_Exception $e) {
-			throw new ServiceException(
-				'Could not get message flag options from IMAP: ' . $e->getMessage(),
-				$e->getCode(),
-				$e
-			);
+			$this->logger->debug('Could not get IMAP PERMANENTFLAGS support; treating custom flags as unsupported', [
+				'exception' => $e,
+				'mailbox' => $mailbox,
+			]);
+
+			return false;
 		}
 		return (is_array($capabilities) === true && array_key_exists('permflags', $capabilities) === true && in_array("\*", $capabilities['permflags'], true) === true);
 	}
diff --git a/tests/Unit/Service/MailManagerTest.php b/tests/Unit/Service/MailManagerTest.php
index 5bd24acc40..3c3df9e7bb 100644
--- a/tests/Unit/Service/MailManagerTest.php
+++ b/tests/Unit/Service/MailManagerTest.php
@@ -10,6 +10,7 @@
 namespace OCA\Mail\Tests\Unit\Service;
 
 use ChristophWurst\Nextcloud\Testing\TestCase;
+use Horde_Imap_Client_Exception;
 use Horde_Imap_Client_Socket;
 use OCA\Mail\Account;
 use OCA\Mail\Attachment;
@@ -404,6 +405,24 @@ public function testIsPermflagsEnabledFalse(): void {
 		$this->assertFalse($this->manager->isPermflagsEnabled($client, $account, 'INBOX'));
 	}
 
+	public function testIsPermflagsEnabledReturnsFalseOnImapError(): void {
+		$account = $this->createStub(Account::class);
+		$client = $this->createMock(Horde_Imap_Client_Socket::class);
+
+		$client->expects($this->once())
+			->method('status')
+			->with('INBOX', \Horde_Imap_Client::STATUS_PERMFLAGS)
+			->willThrowException(new Horde_Imap_Client_Exception('IMAP error reported by server.'));
+		$this->logger->expects($this->once())
+			->method('debug')
+			->with(
+				'Could not get IMAP PERMANENTFLAGS support; treating custom flags as unsupported',
+				$this->callback(static fn (array $context): bool => $context['mailbox'] === 'INBOX' && $context['exception'] instanceof Horde_Imap_Client_Exception),
+			);
+
+		$this->assertFalse($this->manager->isPermflagsEnabled($client, $account, 'INBOX'));
+	}
+
 	public function testRemoveFlag(): void {
 		$client = $this->createStub(Horde_Imap_Client_Socket::class);
 		$account = $this->createStub(Account::class);