I have an exchange 2010 environment where 2013 was introduced for migration and upgradation. Both the servers are in the same subnet. While testing the mail flow between the environment:
- Mails from 2013 mailbox are getting delivered to 2010 mailbox and to external email(gmail etc..)
-Mails sent to 2013 mailbox(irrespective of the source mailbox-2010 or external) are NOT getting delivered to the inbox.
While troubleshooting and tracking i found following things:
1. The mails with 2013 mailbox as their destination are stuck in the retry queue of 2010 hub server(i.e the mails are reaching in the environment)
2. message tracking logs show message as received whereas it is not.
3. i checked the anonymous user in the default receive connector of 2013, but it did not help
4. dns settings and nslookup are all fine.
what could be the possible reason for such a behaviour on exchange 2013 or 2010.