I'm a bit at the end of my rope with this one, I can't seem to find any answers anywhere.
I have email forwarding to a mailbox that worked for more than a year, then one morning it started bouncing and hasn't worked since.
The domain is registered with a company that gives free forwarding so all email for ~@thedomain.co.uk is forwarded to email@example.com which has a POP3 mailbox.
The company that does the forwarding is blaming the company that actually holds the mailbox and the company that holds the mailbox is blaming the company that does the forwarding. However, in this case the error information in the headers is a bit bland and it's hard to pressure either company.
The test is sending from firstname.lastname@example.org to email@example.com which should then be forwarded to firstname.lastname@example.org.
Delivery to the following recipient failed permanently:
Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domain thedomain.co.uk by mx0.123-reg.co.uk. [18.104.22.168].
The error that the other server returned was: 550-Callout verification failed: 550 550 ... Policy not satisfied
It looks to me like the 123-reg.co.uk server (which is the company doing the forwarding and with whom the domain is registered) are rejecting the email, however, if I send an email from a non-freemail service then the email is forwarded with no problems (sending from Hotmail fails as well).
Also, if I send directly to the mailbox from Gmail or Hotmail then it also sends fine.
So if I send from Gmail/Hotmail to the forwarding address it bounces, from Gmail/Hotmail direct to the mailbox address works fine and from a corporate email (inhouse server) to either the mailbox or forwarding address works fine.
If anyone could give me some info to take to support for either the forwarder or mailbox companies I would be eternally grateful!