One of our clients has a problem with their email. Everyone they send a message to, when the recipient gets it, it automatically goes into the Junk Mail folder. I thought there might be something wrong with the reverse DNS lookup, but that was correct. I also checked the Blacklists to see if their Exchange Server was blacklisted, but I didn't find anything listed about the server in question. They are using MX Logic.
What should I look at next?