Thunderbird Community Forum

First, I have very limited understanding of software. I need very simple explanations.

Here's my issue. I use Thunderbird on my desktop computer. I have used the Import/Export > Options > Backup Scheduling function to backup my Thunderbird email to my USB/flash drive. I have labelled the backup folder on my flash drive "Thunderbird email backup." That folder contains numerous subfolders including: 1) calendar-data 2) chrome_debugger_profile 3) crashes 4) datareporting 5) extensions 6) ExternalMailFolders 7) Mail 8) minidumps 9) saved-telemetry-pings 10) scheduled-notifications 11) settings 12) shader-cache 13) storage.

Again, these are the subfolders created/named by the Thunderbird Import/Export backup. I HAVE NO IDEA WHAT THESE FOLDERS MEAN.

Here's what I want - it's actually very simple. I want to be able to see (read) my backed up email on my flash drive without using the Thunderbird installed on my computer. I want complete interaction with the backed up email without my desktop Thunderbird - or my online email account - being involved at all.

My understanding is that Thunderbird Portable is supposed to be able to allow me to do that. I downloaded Thunderbird Portable (from https://portableapps.com) to my flash drive but when I tried to access it the first thing it did was try to force me to put in my online account (POP?) information.

I don't want to do that. I just want to open Thunderbird Portable on the flash drive and have it realize that all of my backed up Thunderbird email information is right there in the same flash drive. I want it to just access and use what's right there.

I was really hoping that Thunderbird Portable would simply ask me where to look - in a very user-friendly way! - and I could tell it to go to my "Thunderbird email backup" folder on my flash drive (WHERE ALL MY THUNDERBIRD INFO IS!) and it would simply do just that and provide me with complete Thunderbird service for the backed up email.

Am I missing something? Can someone give me a VERY SIMPLE walk through to do what I would think should be a very simple thing? Thank you. Chris (6/29/26)

PS - I've read the Mozilla Support ARTICLE: Thunderbird Portable (Mozilla Thunderbird, Portable Edition) and other portable apps as alternatives (https://support.mozilla.org/en-US/questions/1285834) and it alludes in general terms to exactly what I want to do but it does not give any step-wise instructions.

06 May 2026 USA Just to inform users:

All mailboxes and all mail in profile are catastrophically and irretrievably deleted when I: 1. Change the location of the profile folder. 2. Make appropriate change in profiles.ini reflecting the location change. 3. Launch Thunderbird in Offline Mode (launching in OFFLINE mode is the fatal event). 4. Mailboxes will appear during this one launched session

    but

5. If Thunderbird is closed while still OFFLINE, then a re-launch of Thunderbird in any state will reveal

     that all mailboxes and all mail have been deleted.

All mailboxes, and of course, all mail in the profile are catastrophically and irretrievably deleted. I was lucky that I made a backup before changing profile location.

The deletion of mail and mailboxes occur at the close of Thunderbird's OFFLINE state. An examination of the profile folder indicates the destruction has occurred upon closing of Thunderbird in OFFLINE state.

It is not the re-launch of Thunderbird that causes the catastrophic deletion. The deletion occurred when Thunderbird was closed in its OFFLINE state.

To successfully change the profile location I must: 1. Make the change to profile location. 2. Make the appropriate change to profiles.ini 3. BE SURE to make the FIRST LAUNCH of Thunderbird in ONLINE mode--ONLINE only. 4. Once 1,2,3 are done, then Thunderbird does not corrupt the profile folder.

Conditions that MIGHT make my configuration uniquely affected: 1. I use Proton Mail Bridge in conjunction with Thunderbird. 2. My Profile folder is on a network share that is letter-mapped in Windows. 3. I have about 10 email addresses in Thunderbird that are Outlook IMAP, Gmail IMAP, and of course, Proton Mail.

I've been using Thunderbird a couple of years in this configuration with no problems. I just decided to rename my profile. So, this is my first discovery of the problem.