If you're a Thunderbird webmail user & you've noticed that you didn't received any of emails from past few hours / days, then it might be the issue of IMAP Server Settings. You can check it with the help of given steps:
To check the IMAP server settings, tap on the three lines. This will open the menu.
Go to the Options.
Select ‘server settings‘. Check and make sure that you are using the right IMAP server settings for your email.
If the IMAP Server settings is correct in Thunderbird, then you can visit this blog: https://emailspedia.com/thunderbird-is-not-receiving-emails/