> Your own email domain youremail@yourdomain.mozmail.com

I don't understand why would one want to pay for a step down in privacy, voluntarily adding an identifier that allows to track them. The only thing it does is adding some extra information about the alias owner - something that does not make any sense to me, given that the whole point of the service is to obscure users' identities.

I would understand really using my own domain (not this falsey advertising - "foo.mozmail.com" is not something I "own") rather than Mozilla-provided subdomain of theirs. Yea, that would also counter the privacy but at least there's a tradeoff - I retain control of that domain, so if I'm unhappy with Mozilla I still have the email addresses.