Exchange Server - Exchange 2003 clients can no longer send mail via smtp

This developed all of a sudden. POP3 users can no longer send mail via
Outlook, Outlook Express or Microsoft mail. The error message usually
indicates "10060" "socket error". Also we cannot establish a telnet session
on port 25 even though all mail is received by the server and can be picked
up via POP3. The users have no issue sending mail when using OWA.
Even when temporarily disabling the firewall software the problem persist.
Did an Update mess something up here?

All insights are appreciated.

Stephen

What version of Exchange?
--
Ed Crowley MVP
.

I would suggest checking your Exchange Server event log for any related
errors.  I would also suggest running ExBPA to see if it finds anything.
Are you using a Third Party POP3 Connector or Small Business Server?  As Ed
stated, version of Exchange would be helpful.

--
John Oliver, Jr
MCSE, MCT, CCNA
Exchange MVP 2010
Microsoft Certified Partner

Sorry guy's it is Exchange Server 2003 we are dealing with here.
I could not find a BPA tool for 2003. Is there one?
Last night I was able to telnet into the server but still could not connect
via Mail-client. Today no Telnet session on either port 23 or 25. Port 110
and 80 works fine. Could this be a RRAS or Basic Firewall issue?
BTW Exchange server logs are ok.

Thanks for looking into this,

Stephen

ExBPA for Exchange 2003 can be downloaded here,

http://www.microsoft.com/downloads/details.aspx?FamilyID=DBAB201F-4BEE-4943-AC22-E2DDBD258DF3&displaylang=en

Are you running RRAS and/or Firewall on your Exchange Server?  Have you
verified no issues or changes with your ISP?

--
John Oliver, Jr
MCSE, MCT, CCNA
Exchange MVP 2010
Microsoft Certified Partner

Hello John,

Thank you for the link. I installled the BPA tool and it found no problems.
We are using RRAS together with the basic firewall and opened a few needed
ports.
Port 25 and 110 are definitefly open. This server is in a datacenter and the
provider has not changed anything.

Thanks for your responds.

Stephen

I would start with the Firewall and RRAS first.  Your first post you stated
you could not Telnet into port 25 and now you are able too?  If everything
is open properly then mail should flow, so you I would try first by
disabling each one to if mail starts flowing outbound again.  If it does
then you still have a config issue with one of them.

--
John Oliver, Jr
MCSE, MCT, CCNA
Exchange MVP 2010
Microsoft Certified Partner