Tagged with: [ email ] [ exim ] [ mail ] [ subaddressing ]
Sometimes you are looking so hard for a solution, that you won’t even see them even if they punched you in the face. Email Subaddressing is one of those issues I couldn’t get fixed.
Subaddressing, which is something that for instance gmail uses, makes that you can use a plus-sign
+ to add additional data to the local part of an email address. Mail that is sent to
email@example.com will be delivered to firstname.lastname@example.org. But it allows me to see that this email
was sent to me+yourwebsite, which means that this email-address was the one i’ve used to register
myself on onto your website for instance. This makes it very easy to either filter out emails based
on the to-address, track where email-addresses came from (or where the spam was originated from, or
who sold your email address etc).
The thing is: most registration forms on websites are complete and utter crap and do not allow a + sign (or worse: where you must have at least 5 characters for the local part, or even some valid domains that are not recognized etc etc). In those cases, subaddressing do not work.
Most people solve this by using a catch-all on my domains aren’t an option too, because too many spammers sends email to random users.
So here’s the big punch I’ve received this week: you don’t HAVE to use a
+ sign for subaddressing.
Might as well be another character (hell, even a letter!). I know I know.. obvious, but still it hit
me just this week after seeing it in action by somebody else.
Since i’m using virtual domains and users, the only thing i needed to add to my
local_part_suffix = +* : -* : _* local_part_suffix_optional
Which means I can use a plus, a hyphen or even underscores for sub-addressing.