It has come to my attention that some users have reported problems with keystrokes not registering within the compose box of the All-New Yahoo! Mail.
Our engineers are working on the issue, but in the meantime you may be able to resolve it yourself if you make sure your browser is running the most current version of Flash.
To determine the version number please go here:
If it’s older than 9.0.115, please upgrade and then see if the issue continues to happen.
Thank you for your patience while we work to resolve the issue you’ve reported.