Thunderbird Community Forum

Hello, I have a problem with Mozilla Thunderbird. After adding a new email account, it works correctly, but after closing and restarting Thunderbird, the account disappears completely.

In the Thunderbird profile folder, there is no standard prefs.js file. Instead, I have multiple files such as prefs-1.js, prefs-2.js, prefs-3.js, etc.

I use Windows 11 with McAfee. I found information suggesting that this issue may occur when security software prevents Thunderbird from correctly saving or updating prefs.js. I have now completely disabled McAfee.

Could you please advise me how to safely restore the correct prefs.js file and make Thunderbird save the account configuration properly?

Essentially, I want to back up my Thunderbird. The standard way seems to be via Export / Import, but there is an implied limit of 2GB. The export function has successfully ended and produced a file of 15GB. Can I rely on this? (In the sense of being able to Import it should I need to?

Thanks in advance for any help / advice you can give.

I have several MBOX files with me and I want to import MBOX files into the Thunderbird email client. I've come across different methods, including manual techniques and third-party tools, but I'm unsure which approach is the most efficient, especially when dealing with multiple or large-sized MBOX files. Some methods also seem complicated for users who are not very technical.

Suggest me any reliable tool for this!

I live in Morocco. At the weekend our clocks went back 1 hour. However, despite Thunderbird Beta being set to system time for Calendar, it is calculating the time as if my time had not gone back one hour. Any suggestions? Thanks in advance.

For a long time I've been using ublock origin to block parts of emails and RSS feeds to make them more readable. This is not so much to block ads as to block parts that make it hard for me to read things. I am partially sighted. Flashing text etc. is very hard for me.

Now the extension loads but the element hiding part doesn't work on either emails or RSS feeds. I click on it but it no longer selects any part of the emails or feeds.

Why is this and what other options are there?

It still works on Firefox.

Hi! I'm hoping you can help me! I use Thunderbird, and have for many years, and I love it. My computer is on its last legs, and I'm trying to save up for a new one, but, yesterday I did something possibly stupid... (yeah, I know, you NEVER get people asking for help who've done stupid things, so this will be unusual... lol). Anyway... I turned my computer on and got a popup saying that my Thunderbird needs an update and it's been a while since I updated, so I hit OK on the update... Well, my arsehole of a computer chose that exact minute to shit itself and die. When I tried restarting it, my Thunderbird no longer works. Now I have a popup with a big red X that says "The installation seems to be corrupt. Please check your hardware and disk setup and/or re-install." Can you help me? I desperately need to check my email and have one I need to send. I don't know what to do. I've also got YEARS worth of emails sitting in the system, so I can't risk losing them, either. Please help. L.

the latest update has completely messed the inbox. Suddenly all messages "From" field show the same one recipient! An unbelievable mess! Imagine it: you have 50 new messages, from 50 different senders. ALl of them appear "From" one person... How am I supposed to work with this?

Hi, Hoping I can get some help here, I couldn't find an answer in the search topics.

I have lost a few local subfolders. First the subfolders lost the emails contained in them and then the subfolders themselves disappeared.

I renamed the main folder just removing the year from the folder name and not long after that the above happened.

I have tried the following:

• Searching the help topics • Searching the forum • Closing reopening Thunderbird • I removed .msf files and restarted Thunderbird

I am not sure what I can do now.

Thanks in advance for any help.

Hi, Why can't I see or find the calendar in Thunderbird anymore? Is it no longer appearing next to "New Message" like it always did? I have a lot of recurring events on it from the many years I've been using it, and I need to add more events. Please advise. Thanks

For a few days I'm having trouble with Asana mails (notification mails informing me about replies, comments, etc).

Clicking on the mail to view it freezes Thunderbird for a good 5 seconds while one CPU core spins at 100%. This only happens with Asana mails (or at least I haven't found any other problematic senders).

I guess it's a problem with validation or parsing of the mail's HTML content. But I don't know how to debug this.

I can't pinpoint exactly when it started happening, but it was around the time I've switched to the [new snap release track](https://support.mozilla.org/en-US/kb/channel-choices-thunderbird-snap-and-flatpak#w_snap-channel-changes-in-2026). But since this happens with Snap and Flatpak I think the culprit may be the 153.0 update.

Things I've tried:

• Clearing cache and msf files.
• Troubleshooting mode with add-ons disabled.
• Reinstallation. Creating new profile + importing old data.
• Switching from Snap to Flatpak
• Switching Message Body display to Plan Text or Simple HTML.
• Disabling HW acceleration.
• Checking console for suspicious output.

Anything I can do to create handle the problem or collect information for a proper bug report?

After many succesful years using Thunderbird suddenly the update 5.18.0 (64-bit and reporting as supposedly up to date) ) has completely lost all my folders and screwed up my email accounts!! I've been having an absolutely ghastly time for weeks trying to make sense of it and just feel like junking it...HELP! My email accounts that have been working successfully without problem for many years now sometimes send and not receive or the other way round, not send but receive. Additionally I cannot access critical and important emails (serious medical, legal and personal). I tried to change the staus of the accounts from POP to IMAP and ...lo and behold, the program does not allow it!?!? Why the hell not?

9/21/26

Dear T-bird Community Helpers,

      This is my 1st use of any Mozilla mutual help community message board. I'm learning the ropes.

      Re. the OS build: I never use beta anything. I established the folder, that went zero on me, recently (less than 2 weeks ago).  I hadn't yet backed it up onto the cloud or a flash drive or other medium. Was just about to, but thought I'd rename the folder 1st,  9/13.     

      My mistake there, but not in the renaming. Never renamed a T-bird folder before. I had set up Thunderbird the week before 9/13, as a backup to e-mails in my Earthlink WebMail Premium account.      1st as a POP account, then later that week, after checking with a reputable AI interface, I made an IMAP. 

      Today I couldn't find any prior messages in this community board. That I, with my best focus, found relevant to my situation. 

      I try to learn what is involved, first, in decisions between products, accounts, and methods to follow. But I don't have all day. I don't short-shrift research, but I don't have all day.  I relied on an AI bot when I had second thoughts on appropriateness of POP account, and it recommended IMAP account be added. Not substituted for the POP one, though---I asked it about that. too.

      I work hard to learn computer terms but am not deeply skilled with computer stuff.  I cannot generally read between the lines, to infer what sub-step to take to make the next listed step likelier to work. Nor can I understand very unnecessarily complex instructions, so please be feasibly simple in how you instruct me to find a way to restore my local folder. I don't know the exact name it had before. I use spelling tricks to keep folder names short, so there are MANY possibilities for the old name of that folder.

      Your advice, please. I will be grateful for friendly, complete, instructions. Worded simply as is feasible.  And questions 1st, sure, if you need to know more 1st.

         Thank You,
             AK