We are running Exchange 2007 and have been having this intermittent ploblem from a while now. Every so often we get emails which you can see are received in the smtp receive log but the recipient never receives them and there is no other trace that we can find in the message tracking etc. Just seems to dissapear. The emails that sometimes go missing are from companies such as premier inn and various airlines as well as some personal email from the likes of googlemail. From the other logs there is no mention of the emails being rejected as spam. A recent googlemail attempt actually received a "Subject: Delivery Status Notification (Delay)" which gave me an avenue to investigate but so far i have found nothing. > This is an automatically generated Delivery Status Notification > > THIS IS A WARNING MESSAGE ONLY. > > YOU DO NOT NEED TO RESEND YOUR MESSAGE. > > Delivery to the following recipient has been delayed: > > xxxxxx@xxxxx.com> > Message will be retried for 2 more day(s) > > Technical details of temporary failure: > Unspecified Error (SENT_MESSAGE): Connection timed out Any help / pointers appreciated.

So these are messages sent to your domain? External senders are getting these notifications? I would look at networking/firewall issues on your end. Start with the firewall, see if the external SMTP connections are failing there. If possible, ask a sender if their admins can enable SMTP logging on their end and pass along those logs to you.

Hi Andy, Yeah these msgs are to our domain. The exchange logs show the email as coming in so the firewall isnt loosing the smtp. Unless you are saying this could still be the case? As for the other logs i cant see google giving me their smtp logs :-)

Can you post a sample of the full SMTP log on your end of a failed transaction? ANy 3rd party software installed on the Hub Transports that hook in to Exchange? Agents, anti-spam, anti-virus?

Did you checked you POP3 settings, might be you did some mistake over there.

We have removed the tick for ESMTP on the pix policy rule actions as was suggested by someone else and this looks to have cured the problem, only time will tell. Thanks for the help tho guys.