Hotmail Senders receiving NDR : "550-Please turn on SMTP Authentication in your mail client..."
- by DKNUCKLES
Recently, senders from Hotmail have begun to get the following NDR when trying to e-mail our domain.
EDIT : Full NDR Message
Action: failed Status: 5.5.0 Diagnostic-Code: smtp;550-Please turn on
SMTP Authentication in your mail client, or login to the 550-IMAP/POP3
server before sending your message. 550-snt0-omc3-s36.snt0.hotmail.com
[65.55.90.175]:49271 is not permitted to 550 relay through this server
without authentication
This is seemingly out of the blue and I'm at a loss as to why this is happening.
Pertinent Information
We have multiple domains hooked up to our Exchange server. We changed our company name in January of this year, and the old primary domain (olddomain.com) will accept e-mails from Hotmail accounts, however e-mails sent to the new primary domain (newdomain.com) bounce back with the NDR listed above.
The bounces only appear to be happening when the Hotmail sender is sending a new e-mail, and not if they are responding to an e-mail sent from our end.
We have made no changes to the configuration of our server recently. This e-mail first appeared last Friday.
As far as I can tell, the mail doesn't even seem to get to our server
We performed an Exchange 2003 to 2010 migration last year. The 2003 acts as a Smart Host
Any advice on this issue would be greatly appreciated! I'm at a loss
