This is the error that comes back to those who try to send us e-mail
Sorry, we were unable to deliver your message to the following address.
Remote host said: 550 No Such User Here [RCPT_TO]
Windows Server 2003 SBS / Exchange 2003
We are using Barracuda / SpamHaus RBL
This applies to at least 3 of our users and these users have been receiving mail previously with no problems. These users do exist in the Active Directory as well as Exchange.
Looking through Event Viewer I see a few error with MsExchangeTransport / SMTP Protocol EventID 7010 such as
This is an SMTP protocol log for virtual server ID 1, connection #174. The client at "18.104.22.168" sent a "helo" command, and the SMTP server responded with "501 5.5.4 Invalid Address ". The full command sent was "helo .mshome.net". This will probably cause the connection to fail.
However most of those according to blacklists searches are coming from spammers or virus spreaders
I also have a lot of DNS events 6702 (DNS server has updated its own host (A) records. In order to ensure that its DS-integrated peer DNS servers are able to replicate with this server, an attempt was made to update them with the new records through dynamic update. An error was encountered during this update, the record data is the error code.
If this DNS server does not have any DS-integrated peers, then this error
should be ignored. )
There is only one 1 AD in this domain and its not replicating to any others. So im ignoring this.
Restarting the server temporarily fixes this, thats not an aceptable solution however. happens almost every day.