I did my Yahoo account sync with mail 6.3 . I did all the configurations and all the mails are downloaded. Now when I send the mail from browser, the sent mail gets download in mail 6.3 app but when I send the mail from the app it is not getting uploaded onto the yahoo server. This results in the unavailability of sent mails when the mail is accessed from somewhere else. Kindly help for the issue.
MacBook (13-inch Late 2009), OS X Mountain Lion (10.8.3)