[LINK] Why www.etc?

[Glen Turner]

> The '+' is a fairly recent development used only within the Cpanel 
> webhosting system as far as I know.

It's widely used. The syntax is
  user+stuff at domain
where "stuff" does some undefined action depending on the receiving
software.

A common use of gdt+link at example.edu.au is to place the mail into
the "link" folder of the "gdt" account, keeping mailing list mails
out of the INBOX.  The procmail manual page gives an example.

Best wishes, Glen