Just my thoughts: - I would do IMAP (although POP could work and both have similar exposure to any interruption) - check that account settings>synchronization&storage is set for offline use - set File>offline>download to ensure all headers and messages are retrieved - once you have all messages downloaded, I would create filters to separate messages into smaller groups, in Local Folders.

   My reasoning is that Thunderbird could choke, trying to manage 22g of mail in one folder (just my opinion)

- once done, check that all messages are accounted for and then delete the IMAP account. - finally, exit thunderbird and do two backups of the profile folder with WIndows File Explorer

AND, I suggest waiting for other suggestions, as there may be other possibilities in this.

Thank you, David. My emails are classified and stored in folders on the mail server. You suggested that I separate messages into smaller groups in local folders. Does Thunder Bird keep the folder structure when it downloads? If yes, then probably I don't need to create the small groups manually.

Just my thoughts: - I would do IMAP (although POP could work and both have similar exposure to any interruption) - check that account settings>synchronization&storage is set for offline use - set File>offline>download to ensure all headers and messages are retrieved - once you have all messages downloaded, I would create filters to separate messages into smaller groups, in Local Folders. My reasoning is that Thunderbird could choke, trying to manage 22g of mail in one folder (just my opinion) - once done, check that all messages are accounted for and then delete the IMAP account. - finally, exit thunderbird and do two backups of the profile folder with WIndows File Explorer AND, I suggest waiting for other suggestions, as there may be other possibilities in this.

Hi,

How are you accessing your messages now? Do you have a way of exporting them from your expiring server to mbox files? You might be able to do that without having to do anything with Thunderbird, which would make your task easier.

If you can get them into mbox files on your local drive, everything after that is easy.

Rick

Hi, Rick, I access the emails via web browsers. There is no option for me to export emails to local drives. But thank you for this suggestion. I was not aware that there is a such option.

Hi, How are you accessing your messages now? Do you have a way of exporting them from your expiring server to mbox files? You might be able to do that without having to do anything with Thunderbird, which would make your task easier. If you can get them into mbox files on your local drive, everything after that is easy. Rick

On your structure question, if IMAP, the folders will be reconfigured on PC to match what is on server.

Hi yu_chen,

Before you create accounts in Thunderbird, you probably want to set your message format in Thunderbird to "File per message (maildir)".

I believe that performance and reliability of your large message library will be better.

Thunderbird settings - General - at the bottom

I am not an expert. You may want to do your own research.

Rick