SBS2003. No internal email. External unkonwn. Telnet fails on RCPT To: (no response, no error, no timeout)

One of my clients has just advised me that they are not/ have not received email since last friday. Tuesday now although Monday was Holiday.

initially tried to telnet to server.
Connected ok.
Mail From: ok.
rcpt to: No such user (or similar)

Checked the user existed and was not disabled. OK.
Checked services and restarted Exchange. OK. Still Failed
Rebooted Server. OK

Tried to telnet into server again.
helo. OK
mail OK
Reponse takes about 1 min. Then all other commands complete successfully and quickly.

Tried to telnet with rcpt to 3rd party domain.
550 5.7.1 Unable to Relay for .... Again this took about 1 min to respond.

I saw a post that refered to RBLs. There are non configured.
client is running Trend WFBS. Latest version.

it appears to be a delay in the email address lookup to Active Directory maybe. But this is beyond my knowlede and need some help to confirm and fix.

Raoul EdmondsAsked:
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Hii raouledmonds,
Confirm whether they are able to send mails or not..?
Database is in mounted state or not..?
Which version of Exchange they are using and what is the database size.
Also you have to check whether the IP is blacklisted or not.
Can you see any logs in the event viewer that might be of use?
Raoul EdmondsAuthor Commented:
Thanks for the help.

1. Outbound emails are working.
2. Database is Mounted.
3. Exchange 2003. (6.5.7638.1 i think).
3b. priv1.edb = 13.7GB. | priv1.stm = 3.311GB
4. I checked 3 online BlackList search sites. All show the server as NOT listed.

2x. 04/10/2011 1226hrs & 1227hrs (this would be after/during my troubleshooting)
Error 1005. Source MSExchangeSA
Unexpected error <<0xc1050000 - Network problems are preventing connection to the Microsoft Exchange Server computer. An unexpected, unknown error has occurred. Microsoft Exchange Server Information Store ID no: 80040115-0514-000006b5>> occurred.

26x 04/10/2011 between 1227hrs and 1250hrs. (again this was likely while I was troubleshooting)
Error 9175. Source MSExchangeSA
The MAPI call 'OpenMsgStore' failed with the following error:
The Microsoft Exchange Server computer is not available.  Either there are network problems or the Microsoft Exchange Server computer is down for maintenance.
The MAPI provider failed.
Microsoft Exchange Server Information Store
ID no: 8004011d-0526-00000000

LOTS of 9688.
DB approxiching 18GB.

Running Exchange Backup to flush logs now. Will get back to all later.

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please check if all exchange services are running, escpecially the system attendant and transport service

Are the exchange and the DC the same machine?

also, can users use their outlook and OWA as usual?
one more thing, can you deliver mail over telnet internally? i wouldn't expect it, but still
Raoul EdmondsAuthor Commented:
This appeared to resolve itself.

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Raoul EdmondsAuthor Commented:
Situation resolved itself.
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