I am running Exchange 2007 and it has been workig fine since installation (about 90 days) and it has stopped sending mail out from any user. Sent mail leaves the Outbox and leaves the quehue but never arrives it the destination and this happens both internal and external. This service is runnung on 2008 x 64 machine I have reinstslled the DNS service and made changes to the Send connector but i fail to find anything to correct the problem

Anything in message tracking? Enable SMTP protocol logging and see what it shows for messages sent externally. http://technet.microsoft.com/en-us/library/bb124531(EXCHG.80).aspx

Hi Any update for your issue? Please post more infomation about you scenario, and the issue log, what have done before the issue occured. Regards! gavin