Re: 5.5.0 smtp;550 Authentication required

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In news:50E3D786-AE28-4AA5-B9A7-5A5524735936@xxxxxxxxxxxxx,
rjenk <rjenk@xxxxxxxxxxxxxxxxxxxxxxxxx> typed:
I had originally posted this in the SBS newsgroup but it is probably
should be here...

Recently we have began having a rash of mail bounces with the
following information presented:

There was a SMTP communication problem with the recipient's email
server. Please contact your system administrator.

<ourcompanyname.com #5.5.0 smtp;550 Authentication required.

This server has been operating without problems for over a year. The
domain is not blacklisted and I have verified configurations using
www.dnsreport.com. Exchange is configured to use DNS for sending
mail. Is this the issue? We use business class Road Runner. Should
I be forwarding mail to them instead of using DNS?

If you don't have a static IP, or that static IP doesn't have a PTR, or
other suspicious minds out there think that most people sending mail from RR
IPs are spammers, then yeah, you might want to go the smarthost route.



To my knowledge, the server is patched with all of the latest patches
and all systems use Symantec Antivirus Corp.

I have done a great deal of searching but cannot find a concise
answer.

Any help would be appreciated.



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