Merge #2651

2651: Allow + in localpart of addresses to forward to r=mergify[bot] a=nextgens

## What type of PR?

bug-fix

## What does this PR do?

Allow + in localpart of addresses to forward to

### Related issue(s)
- close #1236

## 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/ui/forms.py

@@ -37,7 +37,7 @@ class MultipleEmailAddressesVerify(object):
         self.message = message
 
     def __call__(self, form, field):
-        pattern = re.compile(r'^([_a-z0-9\-]+)(\.[_a-z0-9\-]+)*@([a-z0-9\-]{1,}\.)*([a-z]{1,})(,([_a-z0-9\-]+)(\.[_a-z0-9\-]+)*@([a-z0-9\-]{1,}\.)*([a-z]{2,}))*$')
+        pattern = re.compile(r'^([_a-z0-9\-\+]+)(\.[_a-z0-9\-\+]+)*@([a-z0-9\-]{1,}\.)*([a-z]{1,})(,([_a-z0-9\-\+]+)(\.[_a-z0-9\-\+]+)*@([a-z0-9\-]{1,}\.)*([a-z]{2,}))*$')
         if not pattern.match(field.data.replace(" ", "")):
             raise validators.ValidationError(self.message)
 

towncrier/newsfragments/1236.bugfix

@@ -0,0 +1 @@
+Allow '+' in the localpart of email addresses to forward to