problems with sent email folder

Who is your email provider? Is this an IMAP or POP3 account? Have you confirmed that you have the correct server settings? What error messages do you see? Please quote them precisely and completely. Screen shots would suffice. Do you see the "missing" messages when you go to your provider's web mail interface? Have you checked your Thunderbird settings for what happens when you Send and Delete messages? See: <Account Settings | (the account in question) | Server Settings | "When I delete a message move it to this folder"> and <Account Settings | (the account in question) | Copies & Folders | "When sending messages, automatically place a copy in"> Why is Thunderbird complicated? As Spiderman once said, "With great power comes great responsibility." Which is to say, it has lots of useful features and is very configurable, but it may not be right for everybody. There are other, simpler, less customizable, less feature-full email programs for those who find Thunderbird to be hard to manage. Please don't start multiple threads about the same issue. This seems to be a duplicate of <https://support.mozilla.org/en-US/questions/1591733>.