SBS – No Incoming Mail ‘421 4.3.2 Service not available’

KB ID 0000803


While testing mail flow on a new SBS 2011 Server, outbound mail worked fine, but no mail would flow in. When I attempted to Telnet in from a remote host this was what I saw;

421 4.3.1 Service not available

421 4.3.2 Service not available
Connection to host lost.


Normally I’d expect to see an error like this if the Exchange ‘Receive Connector’ was misconfigured, (if you’re not using SBS 2011 create a new default receive connector and make sure there are no firewalls in the way).

If you are using SBS 2011 you need to run the ‘Connect to the Internet’ Wizard (seriously!)

'Connect to the Internet' Wizard

After this check inbound mail flow again.

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Author: Migrated

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