Problem with mail going to sent folder

[blass12]

I am using a Galaxy S5 (4.4.4) and a yahoo mail account with Aquamail pro. Everything is up to date.

Ive never had an issue before but all of a sudden now, when I send and email from a computer with my yahoo email, they are showing up on my phone in a sent folder. When I send an email from my phone with aquamail, they do not show up in my sent folder.
Also, im not 100% sure, but it seems the emails I send from the computer that show up in my aquamail's sent folder, may not actually even be getting sent to the recipient.
It also seems like its not every email that I send from my computer, it seems like just random emails show up in aquamails sent folder.

Just in general I do not have my email set up for anything to show up in my sent folder. I do not keep sent messages, so its pretty obvious when all of a sudden something is in my sent folder since it is always empty.
The only thing I can think of that has changed over the past few weeks in my phone did update to 4.4.4.
Please help, thanks!

[Kostya Vasilyev]

The "send with desktop mail app -> shows in Aqua" part means that 1) your desktop mail app does save and upload your sent messages and 2) Aqua pulls them down from a folder on Yahoo's mail server.

The "send with Aqua -> message is sent and then gone" part means that you've set Aqua to not save sent messages.

For the "random messages" part it would be useful to check what you see in Yahoo Web Mail.