[@chrishajer Participant 16 years, 12 months ago]

Do you have access to the logs on your server to check for SMTP errors?

Did you try this plugin by sambauers?

https://bbpress.org/forums/topic/email-wont-send-from-anyhting?replies=8#post-13217

This fix is checked into trunk as well, but the plugin might be the easiest way to try the fix.