If the email you sent is not being copied to your Sent Mail folder this is how to check your settings:
First, go to the Gear in the top right and click Settings:
Then click Writing Email in the left side navigation and check the box for saving a copy of mail in your sent mail folder:
When done, click the Save button in the lower left of that window.
If you have the setting checked, but your mail is not saving, try turning on Always use HTTPS in your Yahoo settings.
If your mail is saving sometimes, but getting deleted (disappearing), your account might be compromised:
http://www.emailquestions.com/yahoo-mail/5977-turn-ssl-secure-your-yahoo-mail-account.html
First, go to the Gear in the top right and click Settings:
Then click Writing Email in the left side navigation and check the box for saving a copy of mail in your sent mail folder:
When done, click the Save button in the lower left of that window.
If you have the setting checked, but your mail is not saving, try turning on Always use HTTPS in your Yahoo settings.
If your mail is saving sometimes, but getting deleted (disappearing), your account might be compromised:
http://www.emailquestions.com/yahoo-mail/5977-turn-ssl-secure-your-yahoo-mail-account.html
