Every email service is vulnerable to one or the other problem. Similar is the case with Yahoo Mail. Many Yahoo Mail users have reported facing issue when trying to compose an email in their account. While some are experiencing sluggish response problem, others are not even able to access the compose email window. There can be numerous causes behind this problem; you can trying fixing this problem by following method.
Steps to Fix “Compose Email” Issue in Yahoo Mail Account
First login to login.yahoo.com, then try composing email from the web browser different from the one you were using currently. If you are able to compose email, the problem could be with the cookies and cache of your browser. You will need to delete cookies and cache from your web browser. You can find cookies and cache under the history tab.