diff --git a/lib/Controller/AccountsController.php b/lib/Controller/AccountsController.php
index 81cb19067f..393da826bf 100644
--- a/lib/Controller/AccountsController.php
+++ b/lib/Controller/AccountsController.php
@@ -338,6 +338,12 @@ public function create(string $accountName,
 			$this->logger->info('Creating account disabled by admin.');
 			return MailJsonResponse::error('Could not create account');
 		}
+		if (empty($this->accountService->findByUserIdAndAddress($this->userId, $emailAddress)) === false) {
+			$this->logger->info('Trying to create already existing account.');
+			return MailJsonResponse::fail([
+				'error' => 'ACCOUNT_EXISTS',
+			]);
+		}
 		if (!$this->hostValidator->isValid($imapHost)) {
 			$this->logger->debug('Prevented access to invalid IMAP host', [
 				'host' => $imapHost,
diff --git a/src/components/AccountForm.vue b/src/components/AccountForm.vue
index 217a214c1f..ec5b9c566d 100644
--- a/src/components/AccountForm.vue
+++ b/src/components/AccountForm.vue
@@ -692,6 +692,8 @@ export default {
 					} else if (error.data.service === 'SMTP') {
 						this.feedback = t('mail', 'SMTP server is not reachable')
 					}
+				} else if (error.data?.error === 'ACCOUNT_EXISTS') {
+					this.feedback = t('mail', 'Account already exists')
 				} else if (error.data?.error === 'AUTHENTICATION_WRONG_PASSWORD') {
 					if (error.data.service === 'IMAP') {
 						this.feedback = t('mail', 'IMAP username or password is wrong')