Re: [Fetchmail-users] Local delivery - smtp or sendmail

[Matthias A. <mat...@gm...>]

Am 11.11.25 um 21:24 schrieb Hans Carlson via Fetchmail-users:
> On Tue, 11 Nov 2025, Matthias Andree via Fetchmail-users wrote:
>
>> Am 09.11.25 um 01:50 schrieb Hans Carlson via Fetchmail-users:
>>>
>>>  I'm trying to configure smtpd_sender_restrictions in postfix, 
>>> mainly so
>>>  I'll get an immediate failure if I've added a new email address that
>>>  hasn't been configured in postfix.
>>
>> Those are only available through SMTP, not through most 
>> /usr/{lib,sbin}/sendmail wrappers (certainly not Postfix's).
>
> Right, the restrictions I was planning to configure would only apply 
> to the smtp connections from alpine.  I don't think I want any 
> restrictions on the connections from fetchmail.  fetchmail should 
> process all the mail it gets and deliver it to the local user.
>
> For the smtp connections from alpine on the other hand I want to add a 
> simply table with a list of the email addresses that are allowed to 
> send email.  If in the future I add a new email address, then I want 
> the alpine SMTP connection to my local postfix SMTP server to give me 
> an immediate rejection so I know I need to go configure authentication 
> for the new email address. Without that, the postfix SMTP client 
> connection to the isp relay will eventually fail with an auth error, 
> but I won't notice it for some time because that's all done in the 
> background.
>
> Sooo... if I don't actually want any restrictions on fetchmail, then 
> is there any reason NOT to use sendmail for delivery instead of SMTP?


The concerns are

- you're breaking up the tight coupling between the SMTP server 
(Postfix) and the client (fetchmail), so...

- that you won't notice from fetchmail's end if the Postfix service goes 
down (which it doesn't ever do for me, Postfix is one of the nicer 
things in software) because the sendmail command should always be able 
to enqueue the message, even after "postfix stop", but they won't get 
delivered

[snip]


HTH

Matthias