What is the difference between adding a sender to the blocked senders list and adding a senders domain to the blocked senders list?

If I do the above is it only for one  e-mail address or all my e-mail addresses.

I am getting emails in my inbox to a different email address than mine, I've tried blocking them, but they keep sending them, this is really annoying, can someone help please?
I just received an e-mail with my e-mail address as the sender.  It did not come from me and was a prescription drug company or health products company - because it had them as a link.  How do I stop people from using my e-mail address as a sender

It is saying that my account will be closed down as there has been numerous unsuccessful attempts to sign in so i must update my details.

 I'm sure it is phishing but as I'm a computer dinosaur I would rather be certain.

I hav received an email from Windows Live HotMail (sic) asking me to click on a link and verify my email address and password due to several unsuccessful login attempts on my account.

Is this genuine? Something about it doesn't seem right.

Thanks
Somebody is using my e-mail address. I want to change it. Please help me.
When preparing e-mail messages in Outlook autofill address is not working - how do I repair it/get it to work?