[Mailman-Users] (relatively) new DMARC issues - and Gmail

Lindsay Haisley fmouse at fmp.com
Sat Mar 31 15:35:12 EDT 2018

On Sat, 2018-03-31 at 14:50 -0400, Richard Damon wrote:
> To me the issue sounds like why is fmp.com forwarding spam?
> If this is a case of fmp.com offering forwarding mailboxes to users, who 
> might be using gmail as a final destination, then yes, fmp needs to try 
> to be as good at detecting spam as gmail or users need to accept the 
> increased spam levels.

If pigs could fly ....!  I do the very best job I can of filtering spam
from inbound email, and get about 90% of it, maybe more, but fighting
spam is a forever job of whack-a-mole. I certainly wish that I could do
as good a job of parsing spam from legit email as Gmail does, but I'm a
one-person shop, and have many tasks. Gmail has dozens, perhaps
hundreds of very smart people assigned to managing their spam
filtering, and they do a very good job of it. I could _never_ hope to
match their efficiency or accuracy, nor could most small operations
such as FMP Computer Services.

The problem is that Gmail is whitelisting based on the From address,
rather than the Reply-To address, which should be an _option_ open to
users. On Google's scale of operation, I'm just a fly on a dog turd so
any feature which might benefit my users and subscribers is pretty much
a no-nevermind for them.

> Another option is to deterministically munge the from address so every 
> incoming email address gets a unique fmp address that it represents (it 
> doesn't have to be absolutely unique, mostly unique is likely good 
> enough), something like replace the at with _at_ and add a tail wart 
> like _dmarc at fmp.com (so you can have other addresses an not worry about 
> possible overlaps with those) and use that as the from address. Then a 
> reply will only whitelist that specific original from address.

Which, as I noted in my original post, will cause the Gmail user's mail
account to end up with a whole lot of useless whitelisted address which
would need to be deleted, and FMP's server might well end up getting
blacklisted as a result.

Lindsay Haisley       | "The first casualty when
FMP Computer Services |         war comes is truth."
512-259-1190          |            
http://www.fmp.com    |     -- Hiram W Johnson

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