I would appreciate the following feature. If I open a sent email waiting in the ready to send folder for editing, time doesn’t stop. The timer is still running and a message is sent when the clock runs out. Although I am still editing the message. The message is sent unedited, without the changes I wanted to make.
I would appreciate a stopped timer when I open a message waiting to be sent for editing.
You need to drag the message back to Drafts, then edit it there.
But it is not so handy. If I open a message from the Drafts it is not in editable form 
If I open the dealyed messsage directly it is in editable form and it is much more convenient to edit it.
All messages in Drafts should be editable.
If they aren’t, then it may be because your server has removed the draft flag from the messages. Typically you will have that issue with Yahoo! servers, but some others as well. I gave a solution here.
Thank you, advanced parameter works.
Pavel