use special characters in blog addresses

You mean the hypen as a special character, or mapping domains?

My wordpress multisites have this structure

https://domain.com/BLOGADDRESS1/
https://domain.com/BLOGADDRESS2/

And i would like to give the blogaddress the name of the domain that is linking to it.

my-domain-2.info should link to => https://domain.com/my-domain-2.info/
jan-rulez.net should link to => https://domain.com/jan-rulez.net/

But WordPress does not allow to enter a . in backend.

Is it possible to change that? :S

You should be able to do that as the super admin… Oh, it’s not obvious.

Make it my-domain-2-info

Then go in and EDIT the site from my Sites, and change it to my-domain-2.info

Make sure you do it that way, so you don’t mess up serialization (i.e. it’s important to keep the length of the blog name the same).