We are having the same problem. We have two 5335's with the same problem. We have a dozen copiers including two Xerox 5845. All of those work.
We called our Xerox rep, he said we have the latest version and it was our problem. We did not have the latest version, your version was newer. We down loaded that, installed it and it still did not work. We got a different error message, 016-764.
We also tried the IP address of smtp.gmail.com, no luck. This does not make sense anyway. Sooner or later Google will update that one.
Anything else to try? Or do we just wait for another firmware update.