Every morning for the last two weeks or more I've had to reboot our Exchange Server and often I have to reboot it again during the day. We use a smarthost for sending our mail out and if I view the queues on Exhange System Manager the Small Business SMTP Connector is in a retry state with "The connection was dropped due to an SMTP protocol event sink". I turned logging up to maximum on ExchangeTransport and the only non-information event in EventViewer is “Message delivery to the host '18.104.22.168' failed while delivering to the remote domain 'mail.authsmtp.com' for the following reason: The connection was dropped due to an SMTP protocol event sink. The SMTP verb which caused the error is 'x-exps'. The response from the remote server is ''.”
I stopped using the smarthost during the error condition and all I got was lots of small business connector connections with the same error. I can telnet into mail.authsmtp.com and send a mail during the error state.
Any pointers would be gratefully received.