Originally Posted by DallasBill
KVS... thanks for the RFC, but that doesn't explain how a +xxx still gets to me w/o bouncing back to the sender. If + is valid, then name+xxx
could be another valid email and I would never get it. Unless I am missing something...

<name> & <name+xxx>
are different e-mail addresses. It's the GMail's incoming servers that are set-up in a way that routes all incoming mail for <name+xxx> to the <name> mailbox.