How to Disable the Send Progress Dialog in Thunderbird

Updated July 31, 2019

Thunderbird displays a Sending Message window after you send emails to show how long it's taking to send the message. Depending on the size of the email and the speed of your internet connection and computer, this message may appear for quite a while. If you don't want to see this message, disable it and let Thunderbird send mail in the background, without reporting back to you. Just go into the advanced settings of the email client and change one option to false to make it happen.

Instructions in this article apply to Thunderbird version 60 for Windows.

How to Disable the Send Mail Progress Dialog

To turn off the Sending Message prompt:

Go to Tools > Options.

If you don't see the menu bar at the top of Thunderbird, press the Alt key once to temporarily display it. Go to View > Toolbars > Menu Bar to make the menu bar visible all the time.
In the Options dialog box, select Advanced.
Go to the General tab and choose Config Editor.

If you see a message that reads This might void your warranty, select I accept the risk.
In the about:config dialog box, go to the Search text box and enter show_send_progress.
Double-click or double-tap mailnews.show_send_progress to change the Value to false.
Exit the about:config dialog box.
In the Options dialog box, select OK to save and return to Thunderbird.
From now on, Thunderbird won't show how long it takes to send a message. You can re-enable this feature at any time by repeating Step 5 to change the value to true.