We are a small business and have AT&T business DSL Internet service. We have an Exchange server on site, but use an AT&T SMTP server as a smart host. Some messages we send to hotmail.com addresses deliver fine, however some bounce back with this message:
The following recipient(s) could not be reached:
<user>@hotmail.com on 11/3/2009 8:29 AM
The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator.
< nlpi157.prodigy.net #5.0.0 SMTP; 550 SC-001 Mail rejected by Windows Live Hotmail for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation problems. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help. Email/network admins, please visit http://postmaster.live.com for email delivery information and support>
It appears that nlpi157.prodigy.net is the problem, because the messages to hotmail.com that succeed use a different server (nlpi129.prodigy.net).
We are not having this problem with any addresses other than hotmail.com addresses. Please advise on what steps need to be taken to resolve this problem. Thank you.