....I checked everything and it's all okay,
"everything" is too broad. Please be more specific, and describe what you mean.
but for no reason at all IT JUST DOESN'T DELETE IT!!!
Can somebody help?
Using Thunderbird v2.0.0.6 here
Webmail v.1.2.5
Hotmail add-on 1.2.10b10
I am not using the very latest version of the Hotmail extension because I discovered that it was much slower than this beta version. This works, so I stayed with it.
Here is what I have configured.
In T-Bird, right click on the Hotmail account name. Get a pop up menu.
Choose Properties.
Within Properties of that Hotmail account, go to Server Settings.
On the right side, look for two check boxes.
One is "Leave messages on server"
Below it is "Until I delete them"
I have both checked.
I hope that helps.