Weird one I haven't seen before.
User reported they're unable to email @lampodell.com. Started doing some tests, etc.. tried to telnet to 66.208.230.185 on port 25 and timed out. This was tried from my GWIA box running on Oes2. I then tried to telnet from my windows machine and connected successfully. Found this odd, so looked at my firewall (sonicwall pro 230) logs and when I attempt on linux, it says "malformed IP packet dropped".. this is obviously why we can't email their domain, but I have no idea what would cause this. I'm able to telnet on port 25 to any other domain MX (yahoo, etc).

Any ideas here? lost.