This is probably a network issue more than a thunderbird issue. Copying messages from the online server to local folders requires a lot of interaction. Here is my suggestion to minimize interruptions: - install importexporttools NG addon - click file>offline>download to ensure all message content has downloaded - select the desired messages to move, righrclick and select the importexport option to export as eml - now, click Local Folders, rightclick and select the importexport option to import eml

That's a bit clunky, but it works.

Thank you for your reply. I will try that. I'm just curious what you mean by 'network issue'? I have blazing fast internet (download at +/-315 mbps and upload at 356 mbps). And even if I'm trying to move as few as 5 emails, TB drops one or two of them.

By 'network issue', I am referring to the fact that you are competing with many others for the mail server and a fast internet connection still must cope with traffic. I won't pretend to have the skills to diagnose your connection; I speak only from my own experience.

Finally getting around to trying this. I'm not sure exactly how to follow this step:

click file>offline>download to ensure all message content has downloaded

When I click on 'file' there is an option 'download/sync now'. (See first screenshot attached.) I assume that is the correct one. If I do select that, I have another menu from which I have to choose. What are the correct choices there? (See second screenshot attached.)

Thanks for your help.

Okay, I tried this but it didn't quite work. I already had importexporttools NG addon installed. It shows as v14.1.12, which, as far as I can tell (https://addons.thunderbird.net/en-us/thunderbird/addon/importexporttools-ng/versions/) is the latest version.

Here are the steps I used:

- click file>offline>download/sync now>ok (with 'mail messages' and 'send unsent messages checked') - I selected 745 messages to move, right clicked and selected the importexport option to export as eml. This brought up another menu (see 1st screenshot attached) and I selected 'Messages (Attachments Embedded). - Next, I clicked Local Folders, right click and selected the importexport option to import eml. On the pop-up menu (see 2nd screenshot attached), I selected 'Individual eml messages'.

I noticed that in the folder to which the emails were exported, there were 745 messages but 121 of them were showing a size of 0 bytes. After importing into the Local Folder, only 624 messages were imported, a difference of 121. I received an message indicating 121 errors (see 3rd screenshot). I pressed 'ok' instead of looking looking at the Debug Console, but clearly something went awry. Any thoughts on what I did wrong?

Thanks for your help.

I suggest spot checking several to ensure the messages are fully downloaded. The zero sized messages were just headers.

How do I check that?

Just open the messages to ensure the content is there.

Thanks for your prompt response. I checked a few on the zero btye eml files and they do not have any content. What did I do wrong in the download process?

First, check that same email within the Thunderbird account to see if the content is there. Check also your synchronization&storage settings that you're synchronizing all messages.

I did get it to work and all your suggestions helped. The key was to import using these steps:

ImportExport tools/Export messages as/email message format/message and HTML index

It actually works really well! Thanks for your help.

You are very welcome