Re: [cobalt-users] Blocking email to destination / IP ??

[Larry Smith <lesmith@xxxxxxxxx>]

INRE RE: [cobalt-users] Blocking email to destination / IP ??:
> However, is there a way to do this so that the sender of the message
> gets an error message?  I gather that if the messges are sent to
> /dev/null that they will never know they disappeared... (much the same
> as an incoming "DISCARD" I guess?)

You are correct - /dev/null is the "bit-bucket".

The problem here gets more "complex".   You can put addresses in the access 
file and have a custom error message returned to the sender - _but_ this 
works based on the "sender" address and not the receiver address.

EG:  joe.blow@xxxxxxxxxxxxx     551  No mail from spammers

One could create a "bogus" address, that would always "fail" and then direct 
mail to that, _but_ the problem here is that most spam has forged sender 
addresses so you would just end up with all that mail in your queues or 
bouncing to "postmaster" (admin).

_IF_ you are not using "catch-all" then just do not define a particular 
address and it will fail with "no such user".  Personally I do not allow 
catch-all on our servers because of the problems it creates (any username 
works, regardless and the spammers have a ball)...  I create the aliases that 
are needed (webmaster, admin, etc) for each domain and then let the normal 
mail system "bounce" the remainder (no such user).

-- 
Larry Smith
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