Hi All,I'm new here - so first of all apologies if this isn't the right place for this thread !I'm encountering a problem with exchange where when it is delivering to it's smarthost - some mails are not being delivered.An example from log files of where it goes wrong.. 2008-10-24 15:22:59 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 DATA - - 0 0 4 0 156 SMTP - - - - 2008-10-24 15:22:59 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 354+go+ahead 0 0 12 0 734 SMTP - - - - 2008-10-24 15:23:17 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 250-Message+scanning+in+progress+16:26:28.150 0 0 45 0 18218 SMTP - - - - 2008-10-24 15:23:17 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 RSET - - 0 0 4 0 18234 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 250+ok+1224861996+qp+19506+message+accepted+and+queued+for+scanning+and+delivery 0 0 80 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 MAIL - FROM:<someone@email.co.uk> 0 0 4 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 250+flushed+system+and+ready+for+new+session 0 0 44 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 RCPT - TO:<someone@anotheremail.co.uk> 0 0 4 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 250+ok 0 0 6 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 DATA - - 0 0 4 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 250+ok 0 0 6 0 26109 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionCommand SMTPSVC1 SERVER1 - 25 QUIT - - 0 0 4 0 26140 SMTP - - - - 2008-10-24 15:23:25 10.0.0.5 OutboundConnectionResponse SMTPSVC1 SERVER1 - 25 - - 354+go+ahead 0 0 12 0 26406 SMTP - - - -You can see it all goes wrong when the exchange server issues a RSET in response to the 250-Message+scanning+in+progress.This article http://support.microsoft.com/kb/912341 describes the problem, but despite having applied all updates to 2003 exchange server - the problem still persists.Anybody have any ideas with this ?Thanks,Leon

Hi, Did you check event after diagnostic level up ? and Have you by any chance recreated SMTP virtual server ? please check your Smtpsvc.dll version >= 6.0.3790.2668 again. -MG

Hi Leon, Whats your Exchange version? Is that Exchange 2003 SP2 with the latest updates? Please check Smtpsvc.dll version as MG mentioned. You mentioned some emails were not delivered. Whats the NDR? Please raise up SMTP log level: admin groupyour server namepropertiesdiagnostics loggingMsexchangetransportSMTP protocol. Choose maximum. Then reproduce the issue and see if there is any related errors in event log. Thank you, Elvis

Hi Leon How things are going? If any updates, please post here and we will be glad to help. Regards, Elvis

Hi, Ihad the exact same problem, andit bugged the hell out of me for months, where my clients would occasionally recieve a 5.5.0 NDR when sending an email externally, this would occur several times a day. afterincreasing the event logging for SMTP to highon the exchange server i noticed 3022 and 4007 errors in the event log pertaining to connection problems with the smarthost. are you by any chance using a NetworkBox(r) device as your smarthost? after capturing thetraffic as you have above, we found the same problem when the Smarthost would send the250-Message+scanning+in+progress and then exchange would send a RSET as a reply, then everything would get out of order. the hyphen "-" after the 250 should tell exchange to wait for the next command (i believe it is the AV scan being performed on the smarthost), but for some reason exchange does not recognise this and continues with the RSET then sending the next message. it may be that the first message that is beying scanned is quite large, but even still exchange should recognise the hypen and wait. the resolution we found was to change the setting on the SMTP virtual server in exchange to limit the number of messages per connection to 1! the windows default is 10. this solved the problem as exchange now waits for the session to finish before sending the next message my smtpsvc.dll file version is as follows =6.0.3790.3959 hope this helps, please let me know if it is the same problem and if infact you are using a NetworkBox as your smarthost. and if anyone has a resolution rather than the workaround we found cheers

We're suffering the same problem, and also sending via a Network Box. Exchange only seems to ignore the 250- on some occasions not all. We've tried setting the connector to limit to 1 message per connection, but we still get the same problem occasionally.Love to find a solution!Alan

Hi Alan,Interesting to know that you are running a Network Box as well, it appears that the command is a bit unique to NB but they argue that it complies to the RFC and exchange does not.sorry my solution did not work for you, but it fixed it for me thank god.cheersshazz