Issues with authenticated mail

For PCI reasons, we need to use authenticated email to send everything. This necessitates a minor hack in the core plugin code, changing the headers function to return separate fields for the actual From email and From name. We had it working great until sometime in the first week of May. It seems that two things happened.

1. the plugin got updated and our hack was overwritten
2. something else

I discovered today that our subscribe feature is dead in the water and was able to resolve Thing #1 by putting the changes back in place. That made the fatal errors go away.

I don’t know what Thing #2 is, but it’s causing all mails generated by the plugin to bounce. In our maillog I see “client does not have permission to send as this sender,” even though in settings I’ve configured it as a user with the proper reply-to address for authentication. Maybe a clue to #2 lies in #1… the fatal errors were phpmailerExceptions thrown in wp-includes/class-phpmailer.php — we have an SMTP plugin that’s supposed to be handling email, but it looks like it’s being treated as PHP mail().

WordPress can send email. I have confirmed that two different ways. The problems are limited to the plugin, which can’t send mail at all. It worked until at least May 2, but began failing before May 8.

My secondary suggestion/offer has to do with the headers function, and our hacked version. Could this be incorporated into a future release so it doesn’t have to be altered each time there’s an update?

However, our pressing need is with the bounces. Do you have any advice for how to get the kids to play nicely together again?

Thanks!

https://wordpress.org/plugins/subscribe2/