Not sending activation emails

Replies: 0

I have configured the plugin using Mailgun. Test emails are successfull and repeatable, and I verified that I received the test emails.

However, 100% of new user activation emails are undelivered. The Mailgun interface indicates does NOT indicate that those emails were ever processed, however it does indicate that the test emails were processed.

This is a Multisite set up using a Ubuntu VPS.