Merge #2543

2543: Fix #2231: make public announcements work r=nextgens a=nextgens

## What type of PR?

bug-fix

## What does this PR do?

Ensure public announcements bypass filters.

They can still time-out... but this is already a big improvement that we should be able to backport.

### Related issue(s)
- closes #2231

## 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.

- [ ] 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: Florent Daigniere <nextgens@freenetproject.org>

core/admin/mailu/models.py

@@ -2,7 +2,6 @@
 """
 
 import os
-import smtplib
 import json
 
 from datetime import date
@@ -420,14 +419,19 @@ class Email(object):
 
     def sendmail(self, subject, body):
         """ send an email to the address """
-        f_addr = f'{app.config["POSTMASTER"]}@{idna.encode(app.config["DOMAIN"]).decode("ascii")}'
-        with smtplib.SMTP(app.config['HOST_AUTHSMTP'], port=10025) as smtp:
-            to_address = f'{self.localpart}@{idna.encode(self.domain_name).decode("ascii")}'
-            msg = text.MIMEText(body)
-            msg['Subject'] = subject
-            msg['From'] = f_addr
-            msg['To'] = to_address
-            smtp.sendmail(f_addr, [to_address], msg.as_string())
+        try:
+            f_addr = f'{app.config["POSTMASTER"]}@{idna.encode(app.config["DOMAIN"]).decode("ascii")}'
+            ip, port = app.config['HOST_LMTP'].rsplit(':')
+            with smtplib.LMTP(ip, port=port) as lmtp:
+                to_address = f'{self.localpart}@{idna.encode(self.domain_name).decode("ascii")}'
+                msg = text.MIMEText(body)
+                msg['Subject'] = subject
+                msg['From'] = f_addr
+                msg['To'] = to_address
+                lmtp.sendmail(f_addr, [to_address], msg.as_string())
+            return True
+        except smtplib.SMTPException:
+            return False
 
     @classmethod
     def resolve_domain(cls, email):