I signed up last week and sent myself a 7 meg test message. The next time I checked my mail, I got an error message. Had to report it twice (about 14 hours apart) before it was fixed. My test message never showed up. Sent one that was about 4 megs and it came through fine. Then they changed their interface and my messages were gone. Then the messages were back. I've also noticed that POP access is pretty sketchy. Several times a day, I'll get an error message because my mail client was unable to connect to spymac's server.
On the plus side, it's free and they provide POP access, web space, and picture galleries. I just don't think I'll ever use it as a primary mail drop.