How do you get multiple email addresses on 1 computer?

My email opens with a tab (blinking for attention) no matter which computer or browser I use?

• I run Windows 7. If I turn off the tab I get a note that says messages are waiting and do I really want to close. I have always closed and the tab disappears. A right click and inspection of the element shows a huge amount of HTML and a quick skim showed bits of my emails and contact addresses. Anti Virus and Anti spyware show my computer is clean and it only shows up with yahoo email. The tab looks just like an email that you might have clicked on except it blinks and does not show up in the Inbox. How do I get rid of it and is it some kind of spyware? If so do I need to warn my contacts and take corrective action?

• Answer:

  So you're using an online email viewer or some kind of outlook program? you can disable tabs in the options section of browser and have each new link open in a new window? Found under Yahoo Account Info > Sign-In and Security > View your recent sign-in activity .. interesting, you can restrict sign in locations too.