Sent mail appears in Thunderbird's Inbox

When retrieving mail using Thunderbird, I noticed that all mails that I have sent using the web interface are also downloaded but they are put into the Inbox folder. Obviously, I would like Thunderbird to put them into "Sent" folder. However, over multiple versions this did not change; but the solution is pretty simple. You just have to create a filter redirecting mails sent from your email to the "Sent" folder.

Tools > Message Filters

Redirect sent mail to "Sent" folder