Just a Notepad to block those ads.
See details from TheNonHacker dude.
1. Open Notepad.
2. Open the following file:
C:\Windows\system32\drivers\etc\hosts3. Add the following line at the end of the text file:
127.0.0.1 insider.msg.yahoo.com
Filed under: Web Feature | Tagged: tips and tricks, Yahoo Messenger
Even better is to remove the ads “and” expand your messages into the empty space by using Webmail Ad Blocker
https://addons.mozilla.org/en-US/firefox/addon/7560