Error checking connection

Hi, I use gmail under my own domain for email. If I try and setup bounce handling I am unable to test the connection. I wrote a piece of PHP that calls imap_open with the same parameters and ran it from the server and it successfully connects and shows me all the message headers.

In /includes/class-mailpoet-handle-bounces.php in function imap_connection_check after the call to imap_open you check the connection via if (!$mailbox) (line 136). This is problematic as depending on the server the response will vary, you need to check if ($mailbox = false).

In my case I was then able to test connection and bounce handler is working correctly. It may not cover all scenarios but according to php docs for imap_open this returns false if there is an error.