Some years back I worked in computer administration for a university. At that time we allowed students to pick their own login names. At first the accounts were created by a manual process, so the secretaries who handled the work were given veto power over names they considered too raw. Which turned it into a game of just how spicy a name you could invent and still get it past the secretaries.
Later the process was automated. Students were warned at the outset that it was very hard to change a name -- later we instituted a fee of something like $25 for name changes. And still every year we would get several requests for name changes, along the lines of "My parents just got email capability, so I don't want them to see the name I have been using among my friends."
We also quit doing file backups on the mail server machines, figuring that people have the expectation that when they delete email it is gone. If they store it in their home directories and later delete it, then it will be on the backups for their home directories prior to deletion; but at least if they deleted it immediately on reading it it would indeed be gone.
jhhaynes at earthlink dot net