3 ms·

I believe it is Gmail specific. Cursory search reveals that sendmail does that too, but I don't think it is specified in RFC. Feel free to correct me if I'm wro

• e12e 9y ago
  It's more Sendmail and Exim and others did it, and Gmail does it too - not the other way around;) With qmail the "standard"[1] was username-alias@example.com, rather than username+alias@example.com. I rather prefer that - but then my (user)name(s) don't contain any hyphens. Either way I think it looks better with system usernames - firstname.lastname@example.com was/is usually handled as a separate form of alias look-up anyway. [1] http://www.lifewithqmail.org/lwq.html#dot-qmail-files http://www.lifewithqmail.org/lwq.html#dot-qmail-files See section "4.1.5. extension addresses" [ed: and I recall using tmda as an anti-spam system - it inserts an encrypted tag in the alias portion, that can be stamped with an expiry date, and tied to a sender address (eg hmac(userkey, sender@example.com+01012018) => xyxyzzzzz - give sender@example.com the address user-xyxyzzzz@example.net - and mail to that address will be accepted from only sender@example.com until 1/1/2018. http://tmda.sourceforge.net/cgi-bin/moin.cgi/AboutTmda http://tmda.sourceforge.net/cgi-bin/moin.cgi/AboutTmda ]
• carc1n0gen 9y ago
  I don't have a source to a RFC, but all email's I've ever used let me do this. Including multiple different hosting services with my own domains, and my current work which is MS Exchange.