.well-known creation for each domain

Hello

I have noticed that every domain gets created systematically a .well-know arborescence with email xml config

/var/www/.well-known/blog.mydomain.com/autoconfig/mail/config-v1.1.xml

is this mean to be that way ?
also it doesnt seems to be deleted afterward.

Would it somehow the creation linked to the option in domain config to activate emails in/out ?