Thunderbird Community Forum

My name is graeme , my wife Olivia.

I have many many messages from various people; if I reply to a a mail from "fred", Thunderbird creates a mail:

to: fred@xxxx from: graeme@xxxx

I have several messages from my wife , that behave in this same fashion (ie , as you would expect) but ONE message, when I reply the message displayed in Thunderbird (ie NOT YET SENT, so no SMTP etc yet involved) says:

(it does NOT have a REPLY-TO header BTW)

to: graeme@... from olivia@.....

...I've search back though my mailbox and all the mails from my wife work as you would expect, bar this one ...AND ONE OTHER that I found:

This says:

from olivia@.xxxx to: company@xxxx, olivia@xxxx. graeme@xxxxx

When I hit reply , it generates a message:

from olivia@xxxx to: company@xxxx, olivia@xxxx. graeme@xxxxx

So the from and to in the reply are exactly the same as the from/to in the initial message (they are not swapped)

So, to be clear 99% of messages are fine, it's just one or two cases where I get this odd behavior.

Hello,

Everything working just fine last night. Wake up and Thunderbird will not retrieve emails.

Remembered this old message I got so I went through and deleted my second email address, didn't help.

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

Checked all settings compared to Yahoo, still won't download messages. I can even send a message with my current settings no problem, and it does login, just won't retrieve emails. Gives me a connection timeout.

Anyone have any ideas?

Have not been able to receive email on my primary account (I have 3 accounts) for 3 days now. Windstream has been no help and seems to have lost hundreds of important files. My 2 other accounts work fine. HELP!

My Thunderbird hasn't downloaded emails to my main/default address since mid January. The other two addresses, with all the same settings, and with the same provider, work. Emails are goint to my web mail. I've spent hours on support and on remote control with my provider, and they finally said maybe it's a thunderbird problem. I deleted the programme and reinstalled it, still won't download and all the emails are still missing from my inbox. The emails went missing when I attempted to repair the folders earlier in the saga.. All my local folders are there. I may have to start all over again from a new programme. Thank goodness I can access all emails from my provider's web portal. Aussiebroadband.

I have three email accounts all from different sources.

Two of the three accounts work fine but one account will give me this error message. I back up the Thunderbird folder every week and copied the backup to the working folder and I still have the issue.

I've been getting multiple emails of the same in a few folders. I do have a lot of Filters set up for the account affected.

Can not send emails to a newly created outlook.com (free) account. Have tried dozens of different settings, approaches.

My current setup:

 - windows 10
 - thunderbird 140.8.0esr (64-bit),  numerous previous versions also do not work
 - outlook.com (free) account mail provider
 - POP3 enabled (tried IMAP enabling also) on outlook.com account
 - no 2FA or 2FA enabled on outlook.com account, no difference
 - outlook.com web access works fine
 - followed instructions in mozilla support article Microsoft OAuth Authentication and Thunderbird in 2024 
      (https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202)
 - have done a fresh install on a new machine without an existing profile.
 - have tried various microsoft servers, have tried oauth2, normal password
 - thunderbird account creation works just fine.
 - server settings and SMTP settings match as recommended by support article noted above
    SMTP server settings
        server name: smtp-mail.outlook.com  
        port: 587
        connection: STARTTLS
        authentication: OAUTH2
        user:  xxxxxxxx@outlook.com

symptoms:

 - receiving(downloading) emails works fine.
 - sending emails fails with following messages
     Login to server smtp-mail.outlook.com with username  xxxxxx@outlook.com    failed    followed by 
           Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 
             'Authentication method' in 'Account Settings | Outgoing server (SMTP)'

Many people seem to be having this issue with no resolution.

Please help.

I'm back with an old problem.

When filtering email, it gets interrupted with the error message of:

"The folder "xxxx" could not be found, so filters associated with this folder will be disabled. Verify that the folder exists, and that filters point to a valid destination folder."

Yes, the folder exists.

The previous solution was to change the mail server to imap.googlemail.com. I did that, but connectivity to it has become erratic (it services Germany, Poland, and Russia).

Is there anything else I can do besides use the imap.gmail.com server and keep reenabling the mail filters?

My Thunderbird inbox stopped accepting messages with a message 'Unable to write the email to the mailbox. Make sure the file system allows you write privileges, and you have enough disk space to copy the mailbox.' I 'repaired' the folder but all my junk messages suddenly reappeared in my inbox (a lot of them!). Tools didn;t work (wanted to re-apply junk filter). Went into safe mode - no difference. Now can't get any tools to work on the inbox folder. Not sure what to try next. Help much appreciated.

Emails we are sending to hotmail and outlook accounts are bouncing back and not sending? Is there a reason for this? Can it be fixed by changing server settings? Our hosting company said it is something to do with Thunderbird. Any help greatly appreciated!!!

This is what the bounce back email says:

message that you sent could not be delivered to one or more of its

recipients. This is a permanent error. The following address(es) failed:

15237382@outlook.com host outlook-com.olc.protection.outlook.com [52.101.9.15] SMTP error from remote mail server after pipelined sending data block: 550 5.7.1 Unfortunately, messages from [116.90.5.61] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCD74188716D1A] [BL02EPF0001A0FF.namprd03.prod.outlook.com 2026-02-17T23:03:57.655Z 08DE6BA0C74815DD]

Reporting-MTA: dns; vmse02.mailcluster.com.au

Action: failed Final-Recipient: rfc822;23528273@outlook.com Status: 5.0.0 Remote-MTA: dns; outlook-com.olc.protection.outlook.com Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [116.90.5.61] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BCD74188716D1A] [BL02EPF0001A0FF.namprd03.prod.outlook.com 2026-02-17T23:03:57.655Z 08DE6BA0C74815DD]

I get a notification that includes this message when I try setting up my outlook account and this prevents me from getting mail to my email in Thunderbird, not past or new emails show up and I can only view an empty inbox, contrasting my other emails which work perfectly fine.

When I try setting up my email It says my username or password is wrong when it isn't and when it input, and that I have to put in my login. I put my login in and it says my username and password are incorrect even though my login info is correct I don't know what's going on, the error info isn't very helpful.

I keep getting a large box saying sign into your gmail account using Mozilla Thunderbird, but another box comes up saying error 400 unable to do anything; and the first box keeps reappearing on the screen. My password hasn't changed and I am unable to access gmail. It seems like a corruption between Gmail and Mozilla Thunderbird

Error msg:

Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) outbound failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again.

Attached screen shot.

I'm using gmail/outlook/hotmail email addresses on a new win11 laptop with Surfshark VPN and getting email up & running is the last major set up issue. I am having issues with both send & receive emails across all addresses. I get some functionality if I pause the VPN (not ideal!) but not total. I have tried the Surfshark bypass function for Thunderbird but without success.

I have had no issues with this setup for many years on win10.

Using Outlook (one email address) on the web with the Surfshark Chrome extension I can both send & receive.

1. what should the IMAP & SMTP server settings be for gmail/outlook/hotmail? 2. are there any known issues with Thunderbird/Surfshark? 3. are you aware of any issues with gmail/outlook/hotmail blocking Surfsahrk?

Alan Burdis

will not download -- "Unable to write the email to the mailbox. Make sure the file system allows you write privileges, and you have enough disk space to copy the mailbox"