HACKER Q&A
📣 el_hacker

Why does adding '+FB' to an email still deliver to the original address?


If you send an email to the address ‘hn+fb@gmail.com’, which doesn’t exist, the email will still be delivered to the original address ‘hn@gmail.com’. Why and how is that possible? I think for this to work, the email address should first be used on a Facebook account.”

  👤 curious_curios Accepted Answer ✓
Everything after the plus is considered a sub address and is just an arbitrary tag. You can include any text there and it’ll get delivered to the primary address. It’s useful for filtering emails, and is part of the email spec.
👤 PaulHoule
I understand that the email server has digression on what to do with the local part of the email address. For instance a mail server could take mail to anyaddress@mydomain.com and put it in the "wildcard" box.

I was a qmail fanatic circa 2001 and back then qmail was often configured to put emails to "you@yourdomain.com" to the unix account you and also send "you-*@yourdomain.com" to the you account (anything that starts with "you-")

Of course you can use this to tag email address so if you subscribe to Facebook using "hn-fb@myqmail.com" then emails from Facebook are sent to "hn".

I think the people at gmail thought this was a good idea but that it was better use + instead of - so there you go.

👤 koutetsu
If I'm not mistaken, it's a Gamil specific feature. Any combination of words or numbers between + and @ is seen as not part of your email address but can be used by filter received emails.

See this link for more information: https://gmail.googleblog.com/2008/03/2-hidden-ways-to-get-mo...

👤 nhggfu
don't forget the dot-hack also youremail@gmail.com = y.ouremail@gmail.com = your.email@gmail.com etc
👤 lofaszvanitt
postfix:

recipient_delimiter = +