I have an odd issue with messages being accepted by a external mail server but those customers are reporting they never receive a message. I've verified our brightmail gateway shows the messages are receiving a "deliver message normally" status. A telnet session over port 25 and command "mail from" , "rept to" performed successfully.
We've had our customer support people verify the messages are getting sent to spam or some other custom folder. I've also checked the spam lists and our domain is not blocked but a handful of providers are not delivering the messages.
We are running an Exchange 2010 server.
Thanks for the help.