I presume you still have 'Outlook' installed and all data is in the Outlook default storage location. Try this:

• Tools > Import > Select 'Import from Outlook'
• Click on 'Continue'

follow instructions.

Thank you Toad-Hall for your response. However, I'm missing something from your reply. I have Thunderbird version 115.2.1. I do not see any option that offers importing anything from Outlook version 16.77 on my iMac running Ventura 13.5.2. So, is there another version of Thunderbird that I can install that will allow me to import all of my Outlook emails and folders with all attachments? Thanks again for any help with this.

That import option is there is 102* which I'm still running and I'm running a 118.0b4 beta which also has it.

Whether you use 'Tools' on the 'Menu Bar' toolbar bar OR via Menu app icon > Tools > Import

The image below is what you should be seeing.

Thanks for replying. Version 115.2.2 doesn't have any tool to import Outlook. So, is it SAFE to try and download 118 beta and use that?

The attached picture shows the Import window on TB 115/W10. Note the entry for Outlook, and I don't even have Outlook installed. Not sure if this is a Windows-only option, or a bug in the OS X version.

Thanks sfhowes. I have Outlook version 1808 on my Win11 Pro laptop. But that Outlook is trashed. When I check Thunderbird 115.2.2 on my laptop it does show an option to "Import from Outlook". But on my Imac that option does not appear. I have Outlook version 16.77 on my iMac and it has ALL emails with attachments going back to 2016. Many of these are saved in an INBOX Archive.

I really wanted to move all my email to Thunderbird but it appears that I will not be able to accomplish that for now. I'm hoping that Outlook on my iMac doesn't crash. Or Microsoft doesn't change Outlook again and wipe out most of my emails!!

There apparently is a Thunderbird 118 in development but hasn't been released to the public yet which does have the option for Outlook importing. So, I'll just keep watching for updates. Is there a 116 & 117 version?

I don't know what kind of file INBOX is, but if you can export or save the Outlook data on the Mac as a .pst file, I believe it can be imported to MailStore Home, a free app, on the Windows PC. With MSH, mail can be exported to eml files or mbox files, both of which are easily imported to TB.

It sounds like this import is ok for Windows OS but no on a MAC. I think in a mac they may be called OLM files. I found this: https://support.microsoft.com/en-us/office/export-items-to-an-archive-file-in-outlook-for-mac-281a62bf-cc42-46b1-9ad5-6bda80ca3106

But have a good read of the thread below first as this may offer a way around the problem. https://support.mozilla.org/en-US/questions/1344541

Basically they moved from Outlook to Mac Mail which can create mbox files and then imported mbox files into Thunderbird.