qmail connection died. Possible duplicate! (#4.4.2)

[EQ Admin]

Hello,

Did you get a bounce back message like the following when trying to send an email?

I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.
<username@example.com>:
Connected to x.x.x.x but connection died. Possible duplicate!
(#4.4.2) I'm not going to try again; this message has been in the queue too long.

It's possible that the intended recipient did indeed get one or more copies of the email that you sent.

Possible causes for the duplication include:

• The recipient mail server is overloaded (slow virus/content scanning, etc)
• The recipients mail server did not properly end the smtp conversation (possibly a side effect of the above problem)
• The recipients mail server or network hardware did not end the tcp session properly (try checking a snoop/tcpdump)

You or your ISP should check your outgoing mail logs. If the problem is happening frequently their mail servers or network might be the source of the problem, but most likely the error is being recorded infrequently and the problem will be with the recipients network or mail hosting.