[chrisweekly]

Yeah they're both spec-compliant, but (IIRC, as of a few months ago), in gmail at least, there's a huge difference:

[e-mail] resolves to [e-mail], and the "+acme" is simply a useful bit of metadata for Jane to track the provenance of the sender's mailing list. the "+" and anything following it are ignored. It signifies an optional suffix.

Whereas [e-mail] resolves to [e-mail] -- a completely different address than [e-mail]. The "." is simply ignored as if it weren't there, making j.anedoeacme and jane.doeacme and janedoe.acme equivalent.

Yeah this is specific to how gmail chooses to handle these spec-compliant-though-often-mishandled characters, but anyone who works with email professionally absolutely has to come to terms with how gmail works.