Erros in BETA version

Hi there, can’t share the link and don’T seem to need any more support, but wanted to let you know when I added an account on the BETA 2.2 Version, I got this error:

Warning: Undefined array key "fallback_smtp_password" in /htdocs/wp/wp-content/plugins/post-smtp/Postman/PostmanInputSanitizer.php on line 165

Warning: Cannot modify header information - headers already sent by (output started at /htdocs/wp/wp-content/plugins/post-smtp/Postman/PostmanInputSanitizer.php:165) in /wp/wp-includes/pluggable.php on line 1416

Warning: Cannot modify header information - headers already sent by (output started at /htdocs/wp/wp-content/plugins/post-smtp/Postman/PostmanInputSanitizer.php:165) in /htdocs/wp/wp-includes/pluggable.php on line 1419

Just for your information. After I went back to test the account, everything was fine. So I don’T need help, just wanted to inform you of that error.
Thanks
Anja