Automatically time when a document is opened and closed

[Hidvig]

Hi all

I am trying to create an excel tool that will sit in the background on my teams computers. I want a macro on it that will automatically start running a timer everytime they open an email and automatically stop when they close it. I want this time to then drop onto a second tab on the file and the macro to keep running everytime an email is opened, with the timings all dropping into a big list.

Can it be done??