We are reporting an delivery/bounce issue with a small number of emails dating July 10th.
If you see a bounce message that says “Remote server returned '554 5.4.6 < #5.4.6 X-Postfix; mail for nexttonature.biz loops back to myself>'"
Over the weekend, we made a change to how our servers identify themselves to outside servers in order to try to fix an issue we’ve seen with a few rogue email providers that do extremely strict checking of parts of the SMTP transaction. The change we made had an unforeseen issue - when a MailRoute user of our outbound service sent email a domain that also uses our inbound service, our systems flagged this as a mail loop if (and only if) the email happened to be relayed from one cluster into another server in the exact same cluster (email from one cluster to another was unaffected).
The sender of the message will have received a bounce-back message from our servers or theirs indicating a “mail loop”.
This unfortunate change has been reverted and we are going to explore other ways to try to rectify the issues with those outside servers that led us to this poorly-done change.
Please accept our apologies for the inconvenience this has caused. The issue is now fixed, and outbound email to other MailRoute filtered domains is working properly now.