Done, and don’t work. The same error.
I'm still not clear on where you are putting that code. For that type of code you need to select the button on the stage and then enter the code in the Actions panel.
A better way to code the button is to place it in the timeline where the button lives instead. To do that, select the button on the stage and give the button an instance name in the Properties panel where it says <Instance name>... let's san you name it "btn"
Then create a layer in the timeline for actionscript. If the button is in the first frame of its layer, then select the first frame of the new actions layer and enter the following code in the Actions panel...
btn.onRelease = function(){
trace("btn works");
getURL("mailto:tumail@tumail.com");
}
The trace function inside the the button function should be removed but it is there for now to help make sure that the button is executing the function.