Merge #3897

3897: fix: update ssloptions for fetchmail r=mergify[bot] a=WebSpider

## What type of PR?

bug-fix

## What does this PR do?

Fetchmail has updated SSL behaviour in v6.4.0, causing some unencrypted fetchmail jobs to fail. This repairs the functionality by adding a fallback.

### Related issue(s)
- Closes #3670 

## Prerequisites
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.

- [X] 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/workflow.html#changelog) entry file.


Co-authored-by: Nils Vogels <n.vogels@aves-it.nl>

optional/fetchmail/fetchmail.py

@@ -66,7 +66,7 @@ def run(debug):
         for fetch in fetches:
             fetchmailrc = ""
             options = "options antispam 501, 504, 550, 553, 554"
-            options += " ssl" if fetch["tls"] else ""
+            options += " ssl" if fetch["tls"] else " sslproto \'\'"
             options += " keep" if fetch["keep"] else " fetchall"
             folders = f"folders {",".join(f'"{imaputf7encode(item).replace('"',r"\34")}"' for item in fetch["folders"]) or '"INBOX"'}"
             fetchmailrc += RC_LINE.format(

towncrier/newsfragments/3897.bugfix

@@ -0,0 +1 @@
+Fix fallback for non-ssl fetchmail connections