Here is the (generally) trusty advice from Discourse AI helper:
- Default Email Notifications:
- Activating mailing list mode will override other email notification settings such as the activity summary. Users will receive an email for every new post.
- Muted topics and categories are not included in the emails even in mailing list mode (source).
- Category Exclusions:
- There might be a need to exclude specific categories from mailing list mode. Users have asked if it’s possible to exclude categories from sending emails, particularly for announcements (source).
- Handling Own Posts:
- By default, users do not receive emails for their own posts in mailing list mode. This has led to discussions on whether users should receive copies of their own posts (source).
See also What is “Mailing List mode”?
Take a look at Edit a user preference for everyone or a subset of users