After a bit of deep cave diving into the code I suspect it’s this in model/usermanager.py

This function appears to create a user before it checks to see if the address exists, with the result that multiple users are created when the address already exists.

@implementer(IUserManager) class UserManager: """See IUserManager."""

def create_user(self, email=None, display_name=None):
    """See `IUserManager`."""
    user = User(display_name, Preferences())
    if email:
        address = self.create_address(email, display_name)
        user.link(address)
    return user

this seems to fix the problem - but please don’t trust my solution - needs verification.

@implementer(IUserManager) class UserManager: """See IUserManager."""

def create_user(self, email=None, display_name=None):
    """See `IUserManager`."""
    if email:
        address = self.create_address(email, display_name)
    user = User(display_name, Preferences())
    if email:
        user.link(address)
    return user

On 5 Feb 2015, at 7:59 am, Barry Warsaw <barry@list.org> wrote:

On Feb 05, 2015, at 07:23 AM, Andrew Stuart wrote:

To get the source I do:

bzr branch lp:mailman

Is this the correct way?

I’m using Python 3.4

Yep, exactly so.

Thanks. I'll give it a go tonight. -B