Maybe if you share what these random notifications are, plus the domains of the three email accounts, someone may figure out whatever is your problem. Thank you.

Maybe if you share what these random notifications are, plus the domains of the three email accounts, someone may figure out whatever is your problem. Thank you.

Sorry, I was in a rush and I was not obvious enough. I don't know what are the notifications. A red number appears in the icon (Like when I got a new mail), but when I open the application, no new email, everything is read. The sounds is played, but notification is not shown. (I have thunderbird's notification, not the system's) It stay there until I change the email folder. When I actually getting an email, it's working fine, as expected. All three email is though google. (One @gmail.com, 2 custom domain but both though google) I checked windows notifications too, but nothing is there. Something I'm getting a notification like every 30 minutes.

I have a quite similiar problem: Thunderbird (automatic update to latest release, currently Version 140.2.1esr) on Windows 11. I have several email accounts (gmx, gmail) integrated in Thunderbird. Thunderbird is playing seemingly random a notification sound ("beep") (sometimes several times in 5 minutes, sometimes longer intervalls in between, no pattern discernible). No red number on the Thunderbird task bar icon. When I maximize Thunderbird: There is no new or unread email. I disabled all notification like "play a sound when new message arrives" in the thunderbird settings. Even in the Windows system settings I disabled System>Notifications for the Thunderbird App. If I close Thunderbird completely the annoying sound does not occur any more, so it is clearly created by Thunderbird. Any ideas? This is really annoying...