snoofle:contact your system administrator for assistance at .
Well, according to handling of relative URLs, . means "relative to this directory". Assuming you got this error at http://domain.com/foo then . would mean domain.com (since in an email context, the URL prefix and slashes are irrelevant). So now all you need to do is to work out what the local part is. They seem to be using written "at" to avoid spam crawlers. So whatever's before it would be the local part. So it becomes:
assistance@domain.com
Or it might be that "your system administrator for assistance" is the local part. The spaces are permitted as long as the local part is quoted, so it becomes:
"your system administrator for assistance"@domain.com
Or perhaps they want you to remove the spaces, or replace them with underscores. Guess I'll leave to you to experiment with that one.
See, aren't I helpful? :P </sarcasm>