dovecot - Oct 2020 - Dovecot docker auto-responder - delegate to external SMTP

Hi all,

I have dockerized my dovecot setup. Everything works fine besides 
auto-responder using sieve.

Issue is that the my dovecot docker image does NOT come with a SMTP 
which could be used for outgoing mail.

My SMTP setup (postfix) is in another image/container.

I want to keep it that way, so that dovecot and postfix have separate 
images.

So basically I have 2 containers running in the same internal network: 
a) dovecot IP 192.168.10.11 b) postfix IP 192.168.10.22

How do I have to configure dovecot so that it delegates all outgoing 
(autoresponder) mails to the SMTP on IP 192.168.10.22.

The postfix image is configured in a way that certain IPs are allowed to 
send mails without authentication. So on postfix side I am set.

Currently I did a quickfix: I added postfix to dovecot image and 
configured postfix to use the relayhost 192.168.10.22 for mailing. This 
works, still I would prefer having the dovecot image not containing an 
postfix SMTP.

Thanks

Tom

Hi Thomas,

Did you try to use submission_host configuration parameter in your 
Dovecot container ?

Source : 
https://doc.dovecot.org/configuration_manual/sieve/sieve_and_smtp_submission/

Regards.

Fabien

Le 19/10/2020 ? 12:28, Thomas Pronold a ?crit?:
> Hi all,
>
> I have dockerized my dovecot setup. Everything works fine besides 
> auto-responder using sieve.
>
> Issue is that the my dovecot docker image does NOT come with a SMTP 
> which could be used for outgoing mail.
>
> My SMTP setup (postfix) is in another image/container.
>
> I want to keep it that way, so that dovecot and postfix have separate 
> images.
>
> So basically I have 2 containers running in the same internal network: 
> a) dovecot IP 192.168.10.11 b) postfix IP 192.168.10.22
>
> How do I have to configure dovecot so that it delegates all outgoing 
> (autoresponder) mails to the SMTP on IP 192.168.10.22.
>
> The postfix image is configured in a way that certain IPs are allowed 
> to send mails without authentication. So on postfix side I am set.
>
> Currently I did a quickfix: I added postfix to dovecot image and 
> configured postfix to use the relayhost 192.168.10.22 for mailing. 
> This works, still I would prefer having the dovecot image not 
> containing an postfix SMTP.
>
> Thanks
>
> Tom
>
>

On 19 Oct 2020, at 04:28, Thomas Pronold <mail at tomgrill.de>
wrote:
> The postfix image is configured in a way that certain IPs are allowed to
send mails without authentication. So on postfix side I am set.
This is a *terrible* idea. ALL submissions outside of localhost (of the mail
server) to localdomains should be authenticated, you should never whitelist your
Eps as that just opens you put to abuse.

Yes, my system cron messages from all the non mail servers go to my mail server
over secure submission.

-- 
I want to die in my sleep like my grandfather did, not screaming in
	terror like his passengers.

On Mon, Oct 19, 2020 at 12:28:37PM +0200, Thomas Pronold
wrote:
> I have dockerized my dovecot setup. Everything works fine besides
> auto-responder using sieve.
> 
> Issue is that the my dovecot docker image does NOT come with a SMTP which
> could be used for outgoing mail.
> 
> My SMTP setup (postfix) is in another image/container.
> 
> I want to keep it that way, so that dovecot and postfix have separate
> images.
I use msmtp for that, and install it as sendmail in the container.
It is rather simple SMTP client but quite configurable, and you can
configure TLS and authentication for better security.

-- 
Piotr "Malgond" Auksztulewicz                     firstname at
lastname.net