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?
If you try now, you should be able to do that. We had some server issues.
To change your choice of logins:
Head to your user page.
Then, click the "my logins" button:
Click the "Add more logins..." button.
Then just add a login from the list here:
New comments (answers, updates, etc) show up in the StackExchange Global Inbox in the top right corner of the screen for all Stack Exchange sites. You can opt-in for email updates by clicking the Stack Exchange icon
Select Email Settings at the bottom, and enter the appropriate information
Once you've done so, select Save you'll start receiving emails when ...
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 ...
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.
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.
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 ...
No, it is not possible to change the email of your Stack Exchange Open ID account. As far as Stack Exchange OpenID is concerned, email is your identity. You can't suddenly be someone else.
What you'll need to do is go to your profile and click "my logins". This dialog will allow you to add/remove as many login credentials as you want. From there, add a ...
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.