Thunderbird Community Forum

I am using MacOS 10.13, Thunderbird 115.15.16ESR: my Hotmail worked until 15 May 2025 and then it would not download new emails. Screenshots are available if you want me to post them. I got an error message: "authentication failure while connecting to server outlook.office365.com". I updated Thunderbird to the latest for my OS: 115.18.0ESR. Still no new emails. I deleted my email account on Thunderbird and tried to reinstate it. Now I get an error message when trying to set up the account: "Unable to log in at server. Probably wrong configuration, username or password." I tested my password by logging into my Microsoft account with it on my browser. I can also login to my email using Firefox, but I want my Thunderbird email client to work again.

The configuration I am using is: I use my normal hotmail password in the password field. I also set up a new App Password with Microsoft and tried that without success. With the 115.18 update there is a new field: Your login. I just put my hotmail email address in here. incoming: outlook.office365.com, port 993, SSL/TLS, Oauth2 
outgoing: smtp.office365.com, port 587, STARTTLS, Oauth2 (I have also tried: smtp-mail.outlook.com)

I enabled 2-step authentication with Microsoft in my Microsoft account more than a year ago. Interestingly, I don't get a prompt on my iPhone Microsoft Authentication App when I select Done when trying to set up the hotmail account on Thunderbird.

Please help. I am desperate, and I have wasted a lot of time on this without success. Cheers

I can't send any emails with my personal outlook account. It always says "Login to server smtp.office365.com with username xxx@outlook.com failed." Receiving mails works fine. Both my IMAP and SMTP authentication are set to OAuth2.

Here's my account info found in troubleshooting information.

   account14:
     INCOMING: account14, , (imap) outlook.office365.com:993, 3, 10
     OUTGOING: , SMTP.office365.com:587, 2, 10, true

I've tried:

• Removing and re-adding the account
• Deleting oauth2.issuer and oauth2.scope in config editor and re-login
• Adding the account in a new profile
• Switching to basic authentication for SMTP

They don't solve the issue.

when i oppened tbird on windows 10, it showed a page to obly my for a donation. i had made a donation short ago, but eventhough, i just made another one time donation. when i open tbird again, i can not get out of the donation page. what should i do please???????

Failure to download email from Optus. I have spent a number oif hours to no avail talking and typing with the Optus staff regarding this problem. 1. I can send email from TB but cannot receive. 2. I can see the incoming emails in their Webmail site. 3. Optus confirm my settings are correct for both the mail server and SMTP server. When I go to Settings> Security > Passwords > remove server so I can re-submit my password, the only one showing is the SMTP server. Should the incoming mail server also be shown?

I am frustrated and ready to dump TB but have bee with it many years and don't want to start again with another programme as I am 83 and am partially blind. Please can anyone assist?

Ciao :)

I used to use these add-ons

Old Icon Phoenity Buttons Phoenity Icons

to make Thunderbird more attractive, but now I'm having constant problems. The interface has become schizophrenic, and every time I open it, the icons have a different style, so I've been forced to disable the add-ons.

The question is, are there any supported add-ons left? I can't find any on the website. :(

I try to access my messages from an outlook.com account with Thunderbird mac. I get the error message "the STAT command did not succeed". This happened suddenly today without changing any parameter. POP is enabled on this account. Moreover on another mac with Thunderbird everything is correct with the same account. Cookies are enabled I tried changing OAuth2 to normal and changing back. No sucess. What could I try next? Thanks.

Hi everyone,

I'm working on a privacy-friendly email setup and ran into a challenge with Thunderbird.

My setup: I have a catch-all email address that forwards all incoming emails sent to *@mydomain.com to my real mailbox, secret@mydomain.com. This way, I can use aliases like alias1@mydomain.com, alias2@mydomain.com, etc., without exposing my actual address.

This part works perfectly.

The problem: When replying to a message sent to alias1@mydomain.com, Thunderbird automatically uses secret@mydomain.com as the sender address. That defeats the purpose — the recipient now sees my secret address, which I wanted to keep hidden.

Thunderbird offers a workaround via identities, but it requires creating a separate identity for every single alias, which becomes unmanageable if you use a lot of them.

My attempted solution: My idea was to have my mail server insert a header like:

X-Alias: alias1@mydomain.com

Then, on sending, the server could rewrite the From: header using that value — thus preserving the alias and protecting my actual address.

However, I discovered that Thunderbird strips custom headers like X-Alias when sending. That breaks the solution.

My questions: 1. Is there any way to configure Thunderbird to preserve specific custom headers like X-Alias during sending? 2. Alternatively, is there a better or recommended approach to achieving what I’m trying to do — replying from the alias address automatically, without exposing the real one, and without creating hundreds of identities?

I’d really appreciate any ideas, insights, or suggestions. Thank you!

Hello,

I have saved thousands of emails over the time in several local folders. Near 8Gb of emails with their attached documents. The local folder is in a Synology NAS in my local network.

I was trying to retrieve some of the emails saved in that local folders and found that I couldn't read any of the saved emails. I could see the list of the emails in all the folders but when clicked in one of the emails of the list, nothing was showed.

By saving all the files to the computer, I can read again all the emails. Never happened that it was a problem to read from the NAS. I could see a status bar in the bottom of the window showing the progress in the loading and after a short while, the email and the attached files were shown and loaded.

My local network seems to work ok and also the Synology.

So, my question is, has anything changed that blocks the reading of emails from the local network? Any idea on how to have the emails stored in the NAS?

Thanks

My old Windows10 computer died, but I have an external backup with my Thunderbird profile folder. In the meantime, I have been able to resurrect an old Windows10 computer to continue receiving email, but was not successful transferring the backup profile. Thus, I have "new" profile on this second computer containing only the recent emails not in the backup profile.

I've purchased a new Windows11 computer. My question is: How can I merge my old emails in the backup profile with the recent emails received after the backup was made? In other words, is it possible to merge two separate profiles into one? Thanks.

Illinichip

I have a Suddenlink.net email account that I can't seem to install. Suddenlink has been purchased by Optimum. I have all the requirements that Optimum has given, but it still won't load. my email address is dluenser@suddenlink.net. My password is correct because I can go to their site and get my emails. These are the requirements that they gave me. Again, it is a suddenlink account. Can you help? I've tried numerous times to work with Optimum techs, but they are not knowledgeable to what I should do.

Server Settings by Domain Use the following server settings to set up most third-party email clients or applications to send or receive Optimum email. IMAP (Inbound) Optimum incoming mail server: mail.optimum.net Suddenlink incoming mail server: imap.suddenlink.net Incoming mail port (SSL): 993 (Secure Connection. Recommended if your mail client supports) POP (Inbound) Optimum incoming mail server: mail.optimum.net Suddenlink incoming mail server: pop.suddenlink.net Incoming mail port (SSL): 995 (Secure Connection. Recommended if your mail client supports)

SMTP (Outbound) Optimum outgoing mail server: mail.optimum.net Suddenlink outgoing mail server: smtp.suddenlink.net Outgoing mail port (SSL): 465 (Secure Connection. Recommended if your mail client supports) • Check My SMTP server requires authentication Username and Password (if needed) User Name: Your full email address, including the @domain.net at the end (i.e. @optimum.net, @suddenlink.net) Password: The password for your particular email address • Outgoing server verification/authentication must be enabled and on. If your email client has the option or checkbox that says My outgoing server requires authentication this will need to be checked along with use same settings as my incoming mail server.

Greetings

After updating to 140 (release update channel), IMAP folders keep downloading all emails in a folder, even though the vast majority of them are already local. I get the message "Downloading message x of y in folder" and it goes folder by folder, some of these folders have a lot of mail so this can take ages.

I do have a lot of folders and emails, I have tried compacting and searched for weeks, and only very old and not exactly this issue, any ideas?

Daveed

Windows 11, Thunderbird 140, How to increase the"New Event" box and its Font

- Windows 10, the size is OK

- I have 'Googled" this problem and there seems to be no answer.

Kind regards: Gary Shaw

In microsoft word i have a number of abbrevs that i created (mostly in french, my language) such as bmbm : Bonjour Monsieur, Bonjour Madame, bcdt : bien cordialement mda : merci d'avance etc... there is'nt that many entries so i dont really need to IMPORT (which i have been trying for hours) , i'd be happy to enter them manually again in Thunderbird (im using version nr 91 at mom) but i cannot find out HOW ? tks for your help !

Greetings,

I recently updated to Thunderbird 140. After the update, I am unable to open .eml files by double clicking on them. I receive message window (attached image). If I do File->Open->SavedMessage I can successfully open the file. Please advise how I can get Thunderbird to open .eml files regardless of the instance of Thunderbird that originally created the file.

I shut down my computer on July 6th, went to bed, woke up on July 7th, opened my email to find all of my emails are gone. I had my daughter try and help and the app asked to set up an account. I (grandson) can find the profile and when I dig deeper in Mail I see 4 different inbox folders.

How do I get it to read the older inbox folders?

I have backed up the profile and deleted folder -3.net to try and get it to read the -2.net folder, it just recreates the -3.net folder and the emails only go back to 6/13/25. When I read the other .msf file in notepad I can see the archived emails dating back to 2020-2017. Even found the other folders that were under inbox.

Hi grateful for any help with this please,

When I set the copies and folders setting to place a copy of all sent messages to my email address (IMAP server as i undersand it) it looks fine, but when I actaully send a message andthen look back at the setting it has changed to 'local folders' so the copy is only on the local laptop not accesible elswhere.

This isn't a problem wih an old version of Thunderbird: 102.13.1 (on an old laptop) but on 140.0.1 on a newer machine the problem is there...

Thanks John

My filters seem to work for emails received but not for ones I've sent. I use the rule "From, To, CC or BCC" combined with a persons email name (i.e. preceding the @ sign) and while From works the To doesn't and remain in my sent folder. Periodically I have to use "Run Filters on Folder" or "Run Now" from within the Sent folder to move everything to their respective folders. Do I have to have a separate rule just for "To"?