@Tgr_WMF, I’ve created this subcategory and enabled reply by email. I’ve also set you as the category moderator.
In terms of mailing list mode, any user who sets their notification preferences for this category to “watching” will get an email whenever anything is posted. They can also reply and post via email. Users can also set their site-wide email preferences using “enable mailing list mode”, but this is not category-specific.