Every Webmaster should understand email aliases, an extremely useful feature of most email servers. Pretty much all mail servers allow you to set up aliases. The process is invisible to those who send the messages.
Aliases can serve many useful purposes, besides the obvious one of concealing one's identity.
Alas, all too many people do put aliases to evil uses. His customers don't need to know that he is a lowly AOL user. If he changes ISPs later on, he won't have to change the email address on the site - just the alias. If someone else takes over the webmaster's job, or if an assistant webmaster is added to the team, no hassle - just change the alias. An email alias can be used as a simple mailing list.