Thunderbird is set to download emails on starting and every five minutes, but it doesn't do that, I have to click on "get messages".
Go to Solution.
...After downloading manually it goes back to normal operation.
Bug reports have been filed on this issue. Some, not all, users experience this problem.
A manual request for mail seems to start the auto-downloads again.
You have to go into Account Settings and under Server Settings there is a checkbox 'automatically download new messages'. You can change when it check your messages to download them.
That box is checked and always been.
That box is checked and always has been.
It seems to happen when I have put the computer to sleep (Windows 10). After downloading manually it goes back to normal operation.