If this was working a few days ago, and if you have made no changes, I suggest you contact your email provider, as this appears an error message from the mail server.

Thank you David. I will contact Ionos, but I'm doubtful. I'm trying to move away from Microsoft Outlook, and like a lot of the Thunderbird features, but still have Outlook on my pc and it synched with no problems when I tried using it today.

To get another set of eyes, I suggest posting screenshot of your incoming server settings pane.

Thanks David. I've attached a screen shot.

I've been working with Ionos and they have initiated a "Mailbox Repair Process". This would take a couple of hours. I'll check it tomorrow morning.

That sounds like a solution is coming. There is nothing you can do about that error message; that's why I'm assuming it is a flaw in a script being executed on the server. :) happy 2026!!!!

David,

FYI - I checked Thunderbird this morning and still had the same problem. I did, however, find the solution. I created a new profile and started Thunderbird without creating an email address. I then did a full import from the original profile. It appears that everything is working properly now. Thank you for your help.

John

Thanks for the feedback. I guess we'll never know whether the server repair or the reinstall was the solution. I have never seen that error, but I'm very pleased that you resolved it so easily. :)