Re: How getmail deals with delivery errors and with bounce e-mails

On 03/11/2020 21:26, R. Diez wrote:
> 
>> You are talking about a hosted domain somewhere separate to the ISP ?
>  > [...]
> 
> I am not sure what you mean by that.
> 
> The idea is that your ISP or hoster provides and maintains a web and 
> mail server for very little money for your-domain.com, including virus 
> and spam protection. It is a commodity feature nowadays.
> 
> I know that for us western countries a stable Internet connection is no 
> problem, and paying for managed hosting is no trouble either. Mail 
Well, you're wrong there, but that's not the point.

MDA - Mail Delivery Agent, the thing that puts email into a mailbox.
MTA - Mail Transfer Agent, the thing which sends email around, sendmail, 
postfix, &c.

What you have set-up for email works like this (y is your domain, z is 
your ISP/RSPs domain, a is you at z):
    - Someone spits a message into the ether to x@y
    - eventually it ends up in the mailbox at a@z
It has now been delivered, according the the various RFCs (Requests For 
Comment) that describe how email works.  Feeding "*@y" in "a@z" is the 
end of the chain, the only MTA that can bounce that email is the one at z.

But when you go and grab mail from a@z, it's for x, who doesn't exists, 
and you send a bounce message back, it may be treated as SPAM (or worse) 
by the intervening MTAs, and you and/or your ISPs domain gets 
blacklisted, and that's a real problem.

So don't automatically generate back-scatter.

If you want to tell people that "x@y" does not exists, deliver all 
unknown mail to a catch-all mailbox and do it manually.

You'll probably find that 99% is SPAM, and the other 1% are typos from 
people who won't respond anyway.

(This message might come across a bit harsh, I've dealt with these 
problems a few times in the last thirty-mumble years, it may have pushed 
my BOFH button.  :-) )

	Cheers,
		Gary	B-)