e-mail addresses and “sub-addressing” and “plus addressing” resp. “plussing”

e-mail messages addressing John.Doe+MailingListName@gmail.com are meant to actually go to johndoe@gmail.com, in other words:

  • “.” characters actually get removed for computing the real mail box
  • everything starting the “+” character and going to the “@” character (not including the latter) gets removed entirely

On the recipient side, software can check on plussing and may come to decisions based on the string between the “+” and the “@”.

Yes, gmail and hotmail and posteo do support plussing. GMX does not support plussing.

On my domains I have a catch-all rule for e-mail forwarding aliases, and procmail rules help me with the checks.

When I will get around to it, I will write here under “e-mail”, how I make use of IMAP, procmail, and fetchmail.

Update 2023-04-04: There is another variant of sub-addressing: if you own the full right side of the “@”, you can also use the full left side of the “@” as a “catch all”, i.e. mail_jh@John.Doe.name and mail_aw@John.Doe.name can be John Doe’s dedicated mail address for me (Jochen Hayek) resp. “aw” (like Alex Winner).


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