Here's how:

1. Click Options in the upper right of your Mail page and select Mail Options.
2. On the Options page, in the "Management" column, click on General Preferences.
3. Find the "Composing E-mails" section, "Mode:", and choose Compose messages as plain text.
4. Scroll to the bottom and click the Save button.

Now try it. Can you Compose, Reply to a message or Forward?

If yes, great! But if you're still having trouble Composing, Replying to a message or Forwarding, please click 'Contact Us' below, because we would like to resolve this and get your account working properly as quickly as possible.

Include your Yahoo! ID, and list each step you have already taken. Thanks!