Short answer: YES!
Emails in questions/answers pose at least 2 problems:
Spam: Spambots are very good at filtering plain text emails off websites. (This is why most people, when sharing emails, type them name AT host DOT com etc)
The site doesn't work this way. Questions should be asked here as well as answered here and the problem should be discussed ...
In the preferences screen in your user account you can enable this:
To subscribe to a question click the star underneath the voting arrows.
Is there a possibility to create/save a list of favorite/useful questions?
The email preference that you edited is not the login information that is being used to log in, but the main contact email that Stack Exchange would use to contact you (newsletters, notification digests, etc).
If you want to modify your previous login method, you need to remove it from Profile > Edit Profile & Settings > My Logins instead of Edit Email ...
Emails are not sent as soon as someone posts an answer or comments.
Emails in Stack Exchange websites are more like digests.
The way they work is, if you don't check your notification messages (The ones in the top left, where it says `StackExchange) for a certain amount of time (depending on your preferences), you get an email saying:
1 new item in your ...
(Moved here from comment)
Most MUAs (mail reading programs) do not allow by default (for good reasons) the fetching of external images --- it would be a big privacy problem otherwise. The normal behavior should be the one you comment, and you have to actively load external images to see them.
The only Hot Questions feed I can find is the central SE feed. This obviously contains every hot question for every site and every tag. But each item in the feed has enough information to work out what tags apply and what site which means you can process it down.
You could do this with any of a number of tools, but here's a nice simple Yahoo Pipes version:
You can add other OpenID logins. This relies on you having another account elsewhere but any of them will log you into SE globally.
I realise that isn't the same thing as what you're asking but has the same effect.
It seems you cannot just change your log in, I guess one must be active at all times, I don't really know why.
You can however add more here, by clicking the add more logins button, then from the same page you can remove the previous one if you wish.
If for some reason, this still does not work, you can contact the SE team here.
I think you're confusing two things together:
(1) Email Settings
(2) Your Logins
Email Settings lets you set the preferred contact address. If you add additional email addresses to your logins and set StackExchange login passwords you'll have to delink those logins from your account separately.
If you mean the email preference information in Email ...
It seems that there was a bug in the system.
I needed to change my email in the secondary account to something new (instead of blank), then everything worked like it should.
INFINITE THANKS TO @Seth. You're the man, man.