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albevier asked on

Exchanges stopped sending SMTP data

Exchange 2003 with latest SP and patches
W2K3 Server Standard
PIX 501 Firewall

No outgoing email makes it to destination

- Server has been up and running for at least two years so I believe that the PIX SMTP issue is not the cause of the problem
- About six weeks ago all traffic to hotmail stopped. All other traffic continued without interruption
- Followed all troubleshooting ideas from here and Microsoft -  SPF and Reverse DNS verification, regeister with MS Secure ID, verify that we were not listed on any RBLs
- No changes were made to the server configuration
- Moved problem to MS Support and they verified that my server was logging into their's but felt that our server was not transmitting data
- Telneted into my personal (non-hotmail) account and sent data without a problem
- Telneted into hotmail and got 250 return codes when expected but still no email went through to hotmail
- Worked with MS support to the point that they indicated that they needed to adjust their filters to accomodate either our IP or our domain name (they were not specific about what their filters were looking at)
- Several days later NO email is going out to ANY domain so something outside of MS Hotmail is going on.
- Still receive incoming email

Below an SMTP log from a single email sent to two domains - hotmail and mydomain (Date, Time and other column have been removed to make it cleaner.) Everything looks good but no email was received and either domain.

QUESTION: is there a way from the logs to verify that data was actually transmitted? Response - 25 - - 220+bay0-mc5-f18.bay0.hotmail.com+Sending+unsolicited+commercial+or+bulk+e-mail+to+Microsoft's+computer+network+is+prohibited.+Other+restrictions+are+found+at+http://privacy.msn.com/Anti-spam/.+Violations+will+result+in+use+of+equipment+located+in+California+and+other+states.+Mon,+26+May+2008+08:37:16+-0700+ 0 0 309 0 203 SMTP Command - 25 HELO - mail.mydomain.com 0 0 4 0 203 SMTP Response - 25 - - 250+bay0-mc5-f18.bay0.hotmail.com+([] 0 0 66 0 296 SMTP Command - 25 MAIL - FROM:<admin@mydomain.com> 0 0 4 0 296 SMTP Response - 25 - - 220+spamfilter-21.isp.com 0 0 26 0 203 SMTP Command - 25 HELO - mail.mydomain.com 0 0 4 0 203 SMTP Response - 25 - - 250+admin@mydomain.com....Sender+OK 0 0 46 0 421 SMTP Command - 25 RCPT - TO:<randomtestacct@hotmail.com> 0 0 4 0 421 SMTP Response - 25 - - 250+randomtestacct@hotmail.com+ 0 0 31 0 531 SMTP Command - 25 RCPT - TO:<user@hotmail.com> 0 0 4 0 531 SMTP Response - 25 - - 250+user@hotmail.com+ 0 0 25 0 656 SMTP Command - 25 DATA - - 0 0 4 0 656 SMTP Response - 25 - - 354+Please+start+mail+input. 0 0 28 0 656 SMTP Response - 25 - - 250+Mail+queued+for+delivery. 0 0 29 0 656 SMTP Command - 25 QUIT - - 0 0 4 0 656 SMTP

This has got to be resolved asap.

Thanks in advance for your help.

Email ProtocolsExchange

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Last Comment

8/22/2022 - Mon

Email is flowing to domains other than hotmail.  For whatever reason the test email I sent today was simply delayed for about three hours and led me to believe that all email has stopped flowing.


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The domain is domain.org and the IP address of the sending server is 75.x.x.x

Have to admit to being very hesitant to publish the name and IP so I'd appreciate the washing of the info once the question has been answered.

Update: MS Support is still attempting to "mitigate" my problems but I think they have also hit a wall as they simply repeat requests for me to send them a test message which they then say they did not recieve - would I please send them a test message. I'm not beating up on MS (well..... ok, maybe a little bit.) They have been very responsive especially given the size of the organization.


OK, that done, I need to know how you are sending mail out.

Can you successfully email any remote addresses like GMail?  If so, can you do that and post the headers here (I can tidy them up if necessary)
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William Peck

Sorry for the delay in a response. Took the long weekend off and then got hit with several other issues.

Went to set up a GMAIL account and snag a larger bit of the SMTP logs to craft an aswer to your questions and low and behold, hotmail has started to recieve messages sent from the problem IP/domain!!!!!

No changes were made on our system so I have to assume that Microsoft re-configured one or more of their email servers or that I just happen to be getting routed through to a server that is allowing my traffic.

In case it will help others;
- SMTP and Telnet sessions to any domain other than hotmail (and msn) from any server or workstation on the network was successful
- SMTP and Telnet sessions to hotmail showed 250 codes for all steps (connection, acceptance of Mail From: and Rcpt To: and Data commands) but the messages were never received
- Microsoft indicated that they could see our SMTP server and Telnet session connect but from their perspective, no data was ever sent to them.
- It is not clear to me exactly what they meant by that statement. Looking at either the telnet session capture or our SMTP logs, their SMTP servers were accepting data or at least returning a 250 code all the way along to and including the Quit command.  

I recieved two conflicting messages from Microsoft
1. that they were "mitigating" our problem at the level of their filters
2. that clearly nothing was wrong with their servers, mine were just not sending any data after connection (neither the fact that a telnet session did not work nor the fact that the logs show an acceptance of data ever directly addressed.)

I could not get much out of them beyond a semi-canned response telling me I should re-check my connections and work with my ISP. I just never got to a support group high enough in the food chain.

I have to believe that a filter had been implemented somewhere in the stream directly behind their SMTP servers that blocked our IP address or possibly our domain.

But it works so who am I to complain?

Seems I have to give out all or nothing in points and I couldn't leave you haning with nothing so you get it all. Thanks for working with me.

Good to hear that you sorted it out in the end - I would be very interested to see if it stays fixed now
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