Forum Moderators: phranque
joeuser[b]+tag[/b]@example.com You can use this format when signing up for accounts on various websites and then track who is sending you spam.
There are certainly a lot of sites that espouse the validity of using the plus sign in e-mail addresses. I think the problems you read about with this format are systems that are setup to refuse sending mail with a plus in it. From what I have read these systems violate the standard, but they also make wide use of this format troublesome.