Exchange 2003 SP2 running on a 2003SBS, with BT as the email host ISP.
Every time the server gets a re-boot (typically every few months), a number outgoing emails which had obviously been sticking in Exchange for many weeks then decide to go out and they get phone calls from puzzled recipients saying “I just received your email dated 31st December”, etc.
The SBS Internet Connection wizard settings initially had email set to route via mail.btconnect.com so 6 weeks ago I got a DNS address from BT and changed the Email routing method to the DNS they gave me. All appeared well until last Tuesday when the server had to be re-booted and a mass of old emails, which they believed had been sent out at the time, got sent out and reached their destinations, to the bemusement of the recipients, but also a large batch of NDRs appeared going back to the time of the server’s previous re-boot a month earlier. BT have confirmed the DNS in use is correct. I’m not sure if I should change back to route via mail.btconnect.com. Someone suggested asking BT if using reverse DNS would resolve the issue and someone suggested asking them for a Smarthost, but I’m afraid these terms are new to me and I wouldn’t know where to start or what that would change.
A sample of some of the NDRs read:
smtp;451 Greylisting enabled, try again in 5 minutes
This message was rejected due to the current administrative policy by the destination server
smtp;451 Internal resource temporarily unavailable
smtp;421 Your address has been graylisted
The e-mail system was unable to deliver the message, but did not report a specific reason