550 unauthorized interface for (IP address) 1

[carex]

When attempting to send emails to attg.net or attglobal.net, our workers receive error messages such as the following:

"Your message did not reach some or all of the intended recipients ... The following recipient could not be reached: 'user@attg.net' ... The recipient was unable to take delivery of the message ... 550 unauthorized interface for (our IP address) on in9."

Does anyone know what causes this type of error and what can be done to enable our messages to reach users @attg.net??

Thank you for any answers.

 

[RafRey]

I am having the same problem with user@worldnet.att.net, 550 unauthorized interface.

Did you ever resolve the issue?

 

[dennisbbb]

550 unauthorized interface" means your ip has been banned to forward message to them. Basically they are rejecting anything from your host.

 

[RafRey]

Thanks dennisbbb,

Does this mean that they have a firewall that is blacklisting our domain or our outgoing ip address? I am assuming that this can only be controlled on their end?

 

[dennisbbb]

Yes, your mail certainly reaches their server, because you get an outright rejection response from their server.

 

[dennisbbb]

Some of the reasons you get a rejection to relay message is when you pass their size limit or when your host is blocked by their spam filter via dns blacklist.

 

[carex]

If I remember correctly, to resolve this issue I had to call the receiving ISP's tech support and let them know that we were attempting to send legitimate emails to one of thier customers. I think all I had to do was provide them with our IP and the problem was resolved within a day or two.

 

[cmeagan656]

It may be that attg.net, attglobal.net, etc require you to have a PTR (reverse DNS) entry. If you don't have one contact your ISP and have them set one up for you. AOL, for one, will not accept mail if the sending server does not have a PTR record.

Cheers.