If the message folders are on your PC, you can move them in one of two ways:

1. exit thunderbird, locate the profile folder, copy the desired message folders (probably in Mail\Local Folders folder) to external media. Ignore the msf file. On the Mac, follow same process of exiting thunderbird and copying the message folder to the Mail\Local Folders folder on the Mac.
2. option two is to install the importexporttools addon on both. then, highlight each folder, rightclick, select importexporttools option to export mbox file. Then, on the Mac, highlight Local Folders, rightclick, and select the importexportools option to import mbox. repeat as needed.

However, if you want them all in same folder, use the importexporttools option to export eml and on the Mac,highlight the desired folder, and use the importexporttools option to import eml

Hi David,

Thank you for your response. But your instructions were too general for me to follow with confidence.

It seems that this should be simpler than it is. But I also am not technical. My goal is to merge the two folders from Thunderbird on my PC to Thunderbird on my mac book. And I'd like them all to be accessible within Thunderbird along with the already existing emails on my mac book. I'm not sure if this means the "same folder" as you mentioned.

Is there a way to move the two folders from TB PC to TB Mac manually and have the two moved folders accessible within my already existing mac book TB email?

What folder on mac book should they be moved to in order to access all within mac book TB? And I also would like move my address book/contacts. But that is secondary, unless it can be done at the same time.

Regarding the import/export tool. I did attempt this. The export is easy. It's the import that concerns me. I want to move both the folders. But it didn't seem to allow me to choose those two main folders. It showed all the items in within those folders and there are many. And having never used the import/export tool, I don't want to guess and then overwrite existing emails.

I'm now at a loss of how to move forward. There seems to be so many options I've become more confused. But it seems my goal is very simple. Merge my personal emails from my work PC Thunderbird to my personal Mac book Thunderbird without overwriting the emails already on my Mac book.

I've resigned from my job ironically at a major tech company that I have been at just short of 25 years. I can't bear to loose years of personal emails, many from my parents who both passed away in 2024 with pictures, voicemails, just so many memories.

Are there any visual instructions I can view? Or videos with the steps to follow?

Thanks!!!

Twelve years ago I migrated a friend's Thunderbird profile from a Windows laptop to a MacBook Pro. The migration was very simple and today she still uses the same profile on a new MacBook Pro. I copied the "Thunderbird" folder from ... \AppData\Roaming\Thunderbird\ on the laptop to the MacBook Pro and pasted it in ~/Library/here before launching Thunderbird. Everything was there.

My suggestion: copy the profile folder xxxxxxxx.default-release (or similar name) from the PC to the MacBook where - Thunderbird closed - you paste it in ~/Library/Thunderbird/Profiles/... In the Thunderbird folder on the Mac look up the profiles.ini file and open it with Text-Edit.app. In the paragraph

[General] StartWithLastProfile=1 Version=2

replace the 1 with a 0 (zero) Now when you start TB it will first open the Thunderbird profile manager and propose a list of profiles in which you select the profile you want to start with (image). So you could choose your old migrated PC profile to start with Thunderbird ...

Thanks Mapenzi. I'm realizing now that I left a big part of the process out.

I use proton mail. And in order to use proton mail in Thunderbird I had to use the proton mail bridge. So my Thunderbird might be set up somewhat differently.

I did follow your instructions. I already had 3 profiles on my mac. I added the profile from my pc to the correct file. And I changed the 1 to 0 using Text-Edit.app as you recommended. But when I started Thunderbird and went to choose profile the PC profile I copied from PC to mac library was not pickable.

I'm at a loss of what to do. I posted my question with Proton mail help. If using the bridge does not allow me to merge my emails from my PC then I may need to find another provider.

Magpie, I am very sorry but my instructions from yesterday had a big flaw. After pasting your old profile folder from the PC in the "Profiles" folder of your Thunderbird installation on the MacBook and starting the profile manager Thunderbird could not recognise the old profile since it was still unknown to the profiles.ini file.

I should have written • start TB which will open the profile manager • in the profile manager click on "Create Profile..." which will open a "Create Profile Wizard" • click on "Continue", give a name to the new profile and then click on the "Choose Folder...." button (image) • this will open a Finder navigation window in which you must navigate to your PC profile folder in "Profiles", select the PC profile folder, click "Open" which will bring back the "Create Profile Wizard" • click "Done" which returns to the profile manager window where eventually you click "Start Thunderbird" to open your old profile from the PC