Merge #1635

1635: Add support for AUTH LOGIN authentication mechanism for relaying emai… r=mergify[bot] a=Diman0

…l via smart hosts.

## What type of PR?

Feature

## What does this PR do?

This PR adds support to postfix for AUTH LOGIN authentication mechanism. This enables using smart hosts which only offer AUTH LOGIN. 

### Related issue(s)
- Auto close an issue like: closes #1633

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [n/a] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


Co-authored-by: Dimitri Huisman <diman@huisman.xyz>

core/postfix/Dockerfile

@@ -12,7 +12,7 @@ RUN pip3 install socrate==0.2.0
 RUN pip3 install "podop>0.2.5"
 
 # Image specific layers under this line
-RUN apk add --no-cache postfix postfix-pcre cyrus-sasl-plain
+RUN apk add --no-cache postfix postfix-pcre cyrus-sasl-plain cyrus-sasl-login
 
 COPY conf /conf
 COPY start.py /start.py

towncrier/newsfragments/1635.feature

@@ -0,0 +1 @@
+Add support for AUTH LOGIN authentication mechanism for relaying email via smart hosts.