Question : IIS 6 - Mail server issues

I have 3 mailboxes in IIS 6 on my server 2003 machine, and I'm having issues with 1 of the accounts. When I try to send an e-mail to this account i get an error message:

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 Unknown user - DYN001 (state 14).

I have tried deleting the mailbox/user account on Server 2003 and recreating it, but I'm still getting this problem. The other two mailbox accounts work just fine, and I was using the same incoming/outgoing POP3 settings on all 3 accounts.

Answer : IIS 6 - Mail server issues

perhaps,

I am suggesting that you need to:

a) confirm that it is dyndsn servers that are rejecting the email (look at the NDR mail to check this) and
b) ask DYNDNS to check it out for you.

I think that it is likley that this is the problem.  If they can't/won't fix it then they will at least give you some indication on what you need to do to resolve it.

Cheers.