To fix the upgrade notice from Yahoo Mail recommending you change from CometBird to Internet Explorer or Mozilla Firefox please follow these directions.
First, download and
install the User Agent plugin from this link:
https://addons.mozilla.org/firefox/...ction_id=a9e937f2-2412-5d90-9fb4-a47b09afb3cf
After installing the user agent add-on,
Restart CometBird.
Next, go to the
Tools menu, select
Default User Agent, and click
Edit User Agents:
Click
New and select
New User Agent:
Type in a useful
Description such as "Fix Yahoo Mail - Firefox 25" and then use this string in the
User Agent line:
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:25.0) Gecko/20100101 Firefox/25.0
Click
OK to save the new user agent, then
OK to close the user agent switcher options window.
Now go to
Tools, select
Default User Agent, and
Click the user agent you created in the previous steps:
Open a
new tab in your CometBird and go to
mail.yahoo.com.
As long as you are using the user agent created above you will not be prompted with the web browser upgrade notice.