I've had some trouble with connections to Gmail's SMTP server (due to my host's firewall), but I'm getting what I think is a new error as of a couple of days ago.
SMTP -> ERROR: Failed to connect to server: Connection timed out (110) The following From address failed: <address>@<domain>.org : Called Mail() without being connected
I'm using SMTP, not PHP's mail() function, to send emails. I'm using smtp.gmail.com, port 465, SSL, and SMTP authentication. The email address and password are correct.
Could this be a plugin problem, or is it likely my host's firewall yet again?