[a124556]

With any standards compliant email server you can use "+whatever" in the username and the email should get to you: [e-mail].

[jlgaddis]

"+" is valid in the left-hand side portion and Postfix uses it (by default) as the separator to provide this feature but other mail systems (Qmail and, IIRC, Courier) use "-".

That functionality is not an RFC requirement, however.

[wpietri]

I believe that totally depends on the mail server. If there is an actual standard for that, please do point me to it.