Hi Alan,

Apparently your "Applemac" is a deskop computer? And you want access to the same messages when you are using both your desktop computer and your laptop computer?

The way to do this is to keep messages in IMAP folders, not local folders, so they are synchronized through the server. "Local" means stored on a local drive. You can copy local folders to other computers, but they will be out of date as soon as new messages are stored in them.

What do you mean that you "downloaded" your "Thunderbird account"? What exactly did you do? Are you one of the few people who have a Thunderbird e-mail account so far? Did you copy your Thunderbird profile to your laptop computer? Or did you just set up an account from your e-mail service provider in Thunderbird on your laptop computer?

Hello Rick As you can see I am out of my depth with this problem. I have stored e mails in local folders on my Mac for years. I was hoping to get them in my new MacBook for when I was away. I would not know how to store them in an IMAP folder. What I have done is download the Thunderbird app to my new MacBook and assumed it would also download local folders also. It looks like I am assuming a lot wrongly. How would I store my old e mails in IMAP folders. You are a star for answering so quickly. Alan

First, is your e-mail account IMAP or POP? If you do not know, go to account settings, click on "server settings" in the left pane and note the server type at the top of the right pane. Based on what you have told me so far, I believe that it must be an IMAP account. Let's confirm.

Then, before doing anything else, make a back-up copy of your Thunderbird profile. Even better would be to make a back-up copy of all the important data on your computer if you do not already do that regularly. Ask if you need to learn how to back up a profile.

https://support.mozilla.org/en-US/kb/thunderbird-export

Put the back-up copy (and all back-up copies) on an external drive.

If you have an IMAP account  … 

You know how to create local folders. Creating IMAP folders is the same process. But instead of creating them in the local folders "account", you create them in your e-mail service provider account (Gmail, Microsoft, Apple, Yahoo, AOL, your internet service provider, et al.). Right click on the account name in the folder pane and select "New folder" from the drop-down menu.

At this point, though, you want to copy folders from your local folders to your IMAP account instead of creating new folders. The number of messages could be an issue. How many folders do you want to have access to while you are traveling? How many messages are in each folder?

Here's the process:

1. Make sure that your status toolbar is visible: ≡ menu > Toolbars > Status bar should be checked.
2. Select a small folder in your local folders to start.
3. Right click on that folder and follow the drop-down menu options to copy it to your main e-mail account. Do not move it. It's probably best to copy it to the top level of your account. Do not make it a sub-folder of your inbox.
4. Monitor the copying progress in the status bar at the bottom of Thunderbird's window.
5. After the copying is complete, select the folder that was created in your main account. Verify that it has the right quantity of messages. Uploading many messages to the server will take some time.

Repeat for each folder.

Make another back-up copy of your profile.

Open Thunderbird on your laptop computer. Make sure that the account is subscribed to all the new folders. Right click on the account name, select "Subscribe" from the drop-down menu, and check all the IMAP/server folders that you want copies of on your laptop computer. Give Thunderbird time to download messages into all the folders. Large folders with many messages will take a long time.

Make a back-up copy of the Thunderbird profile on your laptop computer.

When all the local folders that you want access to on both computers have been copied to your main e-mail account and you have made back-up copies of your profiles, you can delete those local folders.

Now every change that you make in one of those IMAP folders will be made in Thunderbird and on the server and then synchronized with the other computer. You will not have to worry about copying messages before or after you travel. It will happen automatically.

Thanks again Rick. I do understand what you are saying but I have a large local folder that I feel is impracticable to effectively duplicate. I have IMAP files. I have decided to merely use the desktop for the purpose of e mail storage. I can aways put them into my local files when I return. I will need to live with not seeing the full history when away from home. I thank you for the time you have spent assisting me today. Not used to carrying a laptop around and need to appreciate their limitations. The next problem will be storing my edited photographs so I will have to work out how I approach things over the two computers including the best cloud options. I thank you so much for explaining things so well. Alan

OK.

May I ask why you believe that putting that folder on the server is impractical? Keeping large folders on servers is common.

Hello Rick Having got a new macbook I am looking to make it as self sufficient as possible by mirroring it’s use to the desktop where I can. It is proving difficult in a couple of areas, retaining copies of saved e mail records being one such area. I rarely let things beat me, hence my original question. I was uncertain about IMAC and POP3 but now I understand ref local files meaning etc. My saved local file in this respect is big and incidentally I do back up my whole desktop to an external file daily. The process you explain does make complete sense but the steps needed are challenging to me personally eg just finding the local files on my hard drive. I am therefore wondering if it is practicable to spend so much time with this task and no doubt getting it wrong at times. In my experience a wrong step on a computer can in itself be complicated to put right.Do I really need this information on the macbook when I only save e mail files once a month and this can continue on the desktop. Thanks again for your invaluable help. Alan

I hear you.

I gave you many details before that may seem scary. Most of the important action is just one command that you give in Thunderbird. No need to look for files on your drive.

If you change your mind, I will guide you step-by-step.

Good luck with whatever you do.