I know this has been posted about before, but I'm a little confused. So, I will present my situation and ask how I should proceed.
So, one of the vendors we work with, for some reason, is unable to send us e-mail. They are running Microsoft Exchange and their Exchange admin says it's us. They never seem to receive a "bounce" message from our server. They receive bounce messages from their server that state that they don't have permission to send us mail. WTH??
I can think of a couple reasons why they cannot send s mail. When you do a reverse lookup on their mail server's IP address, it doesn't match. Also, when we attempt to receive mail from them, I'm not sure if our mail server sees "mail.xxx.com", "internalservername.xxx.local (seen in e-mail headers)", or "exchange.xxx.com (what their admin says we need to add to an 'allow' list)"...all of which would not have a proper information returned on a reverse lookup (expecially the internal .local domain).
The other reason why they may not be able to send us mail is because they ended up on one of the RBL's we use.
Is there a way I can add a domain to a "whitelist" that is read before any RBLs are read or any other spam related checks are done? I know I can give a domain a negative spam score per the instructions on the "Improving Anti-Spam System" wiki entry, but I don't know if this will work. Will it?
If this has already been discussed, I do apologize. Feel free to forward me in the right direction.
Many thanks in advance.