Sorry for the question: I was looking at the problem the wrong way. As the docs say, simply sending an email to LISTNAME-join@DOMAIN is what I need.

BR El lun., 13 ago. 2018 a las 18:37, David Palao (<dpalao.python@gmail.com>) escribió:

Hi, I'm administrating a mailman 2.1 list and I'd like to write a (python) program that sends an invitation to a given email address. Is there a way to do it?

TIA