It's working on my community but I have to test it before I would deploy it.
cough *** cough*** This is an early release, it may delete all your emails - you've been warned!
I would highly recommend looking into a hosted email service like SendGrid. My forum sends over 100k emails per month and, after having dealt with all of the massive headaches with email deliverability issues similar to what you described, I find that it's more than worth the price of their services (or another service like theirs).I'm running into issues where some of the bigger mail providers (yahoo and gmail come to mind) have gone to a process of blocking that is completely automated. I have a user with a valid yahoo address and yahoo thinks anything from the forum to that address is spam. I get a delayed delivery notice, but if you read the actual text, it's really telling you it'll never be delivered and tough luck. I have yet been able to find a link/contact to contest that type of bounce.
And don't get me started on gmail. After years and years of getting server generated messages to my gmail account (security logs, backup reports, etc.), Google started blocking them last summer. After 3 months of fighting it, I finally gave up and changed email providers. At least Microsoft gives you an option of contacting a real person as a last resort to get things resolved. Something Google and Yahoo have failed to do.
Based solely on that, I'd be cautious of wanting the forum to automate any type of action based on bounced emails. If things were to go down this road, I'd prefer that a list/report be generated that required a human to perform any account actions.
I wrote a custom script for use with their Event Webhook API. When a user's email bounces or gets blocked, they send a request back to my script, which looks up the user in the XF database and de-activates their account.How did you integrate sendgrid with xenforo ?