I am trying to help a real estate agency with this same problem. The firmware was updated, which fixed the issue for about a week, but now its happening intermittently again. The settings are right on the Xerox and in the email account. Were you able to find a resolution to your scan to email issue?
That's interesting, I too work in a real estate office and am having a similar issue. When trying to scan (ours is a VersaLink C605) to a particular email address in our office the job goes on and on and finally times out with the 027-773 error. I can email this person via other means and I can scan an email to myself to a mailbox on the same mail server (same SMTP server out and POP in). Our outgoing mail goes through GMail.
I rebooted twice to kill the unsuccessful jobs before letting it run till it failed.