Hi all,
Was hoping someone somewhere can shed some light on an issue we've been seeing for the last 3 days. We are in the middle of an Exchange 2003 to 2010 migration.
Everything was going fine regarding mail flow between both servers and inbound / outbound mail to the internet. However, one team has stopped receiving emails from an application server.
They receive NDR reports with the following message:
#5.7.1 smtp;550 5.7.1 Requested action not taken: message refused> #SMTP#
The users mailboxes are still on the 2003 server. I ran some packet captures on the server which also showed the following message:
Response Code: Requested Action Not Taken: Mailbox Unavailable (550).
What I don't understand is that the mailboxes are available and can receive other emails. I have also checked the SMPTP logs and can see the servers communicating with no errors. I have also sent test emails successfully using telnet to the same mailboxes.
Somehow, the introduction of the new Exchange Server has caused this issue but I cannot figure out what it is. If we point the application server to the Exchange 2010 server, the emails are received on my mailbox which resides on that server, but the messages are not received on the Exchange 2003 server.
If anyone can point me in the right direction it would be a huge help.
Thanks in advance!