When you are moving to a new Plesk Server the Migration Manager of Plesk is a cool feature. It helps you to keep out of a lot of trouble. But unfortunately it also add some trouble.
When you try to migrate a Mailman maillinglist the Migration Manager first adds a new list with default settings and then add user per user to list. But there is on heavy pitfall: The defaults say to send a welcome message to every new user. *bumm*!
So every user will get again (or the first time :-)) the welcome message of the list. In general this isn’t a good idea.
To avoid this problem we need to change the defaults of the Mailman settings. We need to add a line to the file mm_cfg.py Usually you’ll find the file at /usr/lib/mailman/Mailman. Edit the file and add
DEFAULT_SEND_WELCOME_MSG = No
If you like you can take a look at the file Defauls.py in the same directory. There you’ll find all other defaults. If you want to override one of these settings you just need to add an other line to the mm_cfg.py file.