Everything seems to be working following setting this up yesterday on my site (i.e., emails are being sent from the desired address and are no longer going to spam), but my "From Email" field does not match the username for the SMTP host, and I would like to edit the username and password fields. Every time I make this change and click Save Changes, it says "Settings Saved." but immediately reverts back to what was entered before.
I restored a previous snapshot of the site from before I had installed this plug-in, so I'm not sure if that's part of the problem or just a red herring.
Hope someone can help! I really like this plug-in otherwise.