[williamdclt]

Not as useful as `[e-mail]` for example :/

[floatingatoll]

Not as readable, but each inter-character spot is a bit, and if you have 11 bits, you can represent 2^11 addresses.

EDIT: Assumes Zero or One periods per bit-gap; if you can chain them, the sky’s the limit.

[ixwt]

I just tested it with a bunch of periods. I got rejected with just two periods adjacent, and with quite a few more periods adjacent. So only bits. Looks like it can be used for filtering too.

[dimensi0nal]

Dots cannot appear consecutively in the local-part unless quoted.

[macspoofing]

I never understood why that was useful. If you're a spammer that harvests email address or if you're an unscrupulous service that sells your user email address to spammers, wouldn't you simply remove the '+' suffix from any gmail address before commencing your spamming?