As if any email account can be used, for Following.How do I Follow a blog using my HotMail account?
Right now, you can Follow a Blogger blog, using any of 6 different account hosts - 5 outside Blogger / Google authentication space.
The profile displayed, with demographic details, lists of blogs, and such, will vary, depending upon what account host a given Follower is using.
Profiles besides Blogger and Google are supported.
We are most familiar with the Blogger and Google profiles. There are additional profile selections available, which does not equal the account host selections.
You can change your profile selection for each site from the "Site Settings" wizard.
Normal email accounts - like HotMail - don't provide any community infrastructure, and any profile at all. Can you even upload a picture, to HotMail, that would be served by their servers and appear on a Followed blog? Will HotMail serve a profile, to let people browsing any Followed blog see who you are, and what other blogs / websites you have Followed?
You simply need an account on any supported host.
You need an account on a host, that's recognised by Google, and serves a community experience, to Follow any Blogger blog, using Following or Friend Connect. Which account you use will affect both your ability to Block unwanted Followers, and your ability to read the contents of Followed blogs.
It's not difficult to setup a Blogger / Google account.
Fortunately, it's not difficult to setup a Blogger / Google account, based upon any existent (or non existent) non Google account. A Google account does not have to be based on a GMail email address - it can, just as easily, be based upon a HotMail email address - and can be setup in a couple minutes, from the Google "One account" login screen.
(Update 2016/01): Blogger Engineering is now rewriting Following, to make the Followers gadget and the Following service more reliable - and they are eliminating these non Google services from Following. Anybody using any of the non Google services is urged to Follow this blog again - using a Blogger / Google account.