Re: [exim] Address rewriting for spam control

On Wed, 20 Apr 2005, jeff sacksteder wrote:

> In the past, I have found it useful to fabricate addresses for my
> own domain when signing up for services that required valid email
> addresses. For example, if lamesite.com requires me to list an
> address, I'll give them myname-lamesite.com@???, knowing
> that all mail to that domain winds up in my single inbox. This
> scheme has worked rather well to show what domains have distributed
> my address.

indeed

> My problem now is that I need to host several distinct user
> mailboxes on the domain. I want to be able to process incoming
> messages and deliver them to the correct party without configuring
> exim ahead of time with those addresses.

There's a long-standing technique (which I first met in relation to
sendmail) whereby an address of the form

myname+whatever@???

can be delivered to myname at mydomain.example with the "whatever" tag
in place. This is easily implemented in exim - our router says this:

plus_suffix:
driver = redirect
allow_defer
allow_fail
skip_syntax_errors
data = ${local_part}@${domain}
local_part_suffix = "+*"
retry_use_local_part

Unfortunately, I'm increasingly finding that commercial sites declare
addresses with "+" in them to be illegal syntax / invalid address /
whatever, and refuse to accept them in subscriptions etc. Whether
this is deliberate because they know what "+" is used for, or just
sheer ignorance of the RFCs, I couldn't say, but whichever it is, it
makes this specific technique less useful than it could be.

Your plan of using "-" then seems a viable alternative, as long as
it's not already being used as a significant part of your existing
local addresses.

imho and ymmv