I agree with Kurt. Enable SMTP logging and look at the protocol flow. It's usually pretty obvious.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Kurt Buff Sent: Thursday, July 10, 2014 4:41 PM To: [email protected] Subject: Re: [Exchange] SMTP 4.4.2 What's the full text of the NDR? That will provide better clues as to what's happening. However, first guess is that the sending machine is on a blacklist somewhere... Kurt On Thu, Jul 10, 2014 at 12:31 PM, Dave Lum <[email protected]> wrote: > Have you guys seen a 4.4.2 error but only from a specific sender? I am > troubleshooting email where someone we send mail to we're receiving > the > 4.4.2 "lost connection" bounce. > > 1. We have only one recipient domain reporting they can't get email > from us 2. Sending email to them from a GMAIL account simultaneously, > they will receive the GMAIL one but not the other one > > The issue seems to be on their end (as the 4.4.2 would indicate, since > we seem to be able to send to everyone else), but it seems odd that > it's just from us and not Gmail at the same time. > > Ideas? > > Dave > > >
