This is a generic error that can be the result of a couple problems including:Have you seen this NDR before?
Connected to x.x.x.x but connection died. (#4.4.2) I'm not going to try again; this message has been in the queue too long.
- The mail server for the person you are trying to send e-mail to is down
- The mail server for the person you are trying to send e-mail to is dropping the connection before the transaction is done.
- There is a network problem between your SMTP server and their mail server.
- The mail server may be dropping the connection if it believes you are a spam source but not providing that as the reason.
Many times these problems will clear themselves up if you give them a little time.
If the problem persists, check with your ISP and see if they are having troubles or have been blacklisted