We have Exchange 2010 running on a single server for about 50-60 users. Most of them send and receive mail just fine, however a couple of them cannot receive messages from anyone outside the company. They can send ok but no email from a user outside our domain makes it in. I have run the Remote Connectivity Analyzer and it fails the inbound SMTP test with the following error: Message: Mailbox unavailable. The server response was: 5.7.1 Recipient rejected (R4). I have searched and found some information about setting SMTP to deliver to the IP address of the Exchange server but that does not seem to have made a difference. Any suggestions would be welcome.

Thanks,

Hello

tip: set  eventloglevel expert for smtp and active directory topology

MSExchangeADTopology\General
MSExchangeADTopology\Configuration
MSExchangeADTopology\Topology

and try again "Connectivity Analyzer"  and check eventlog.
if have sany spam filter disable before start

Unfortunately I do not have permissions to make these changes, I will have to wait for the lead Exchange admin to return before testing again.

Well this is embarrassing, it turned out to be our spam filter. Just needed to add the users so that their email was passed through. Thanks for the input though.