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Thunderbird downloads new emails for all my emails except one. Has not downloaded on that one since July 3. Have reset various background settings to match other email accounts. Running on Windows 10. Suggestions?

Using the same settings as my main account: imap.gmail.com SSL/TLS 0Auth2 Tried copying in same local directory as one that is working. No idea what all these do...

I have used Thunderbird for years with complete success. Recently (within the past month) I have lost the ability to send (SMTP) mail and receive the following error message: "Send Message Error, Sending of the message failed. Unable to authenticate to Outgoing server (SMTP). Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)." [I just change my from address to another one going through Network Solutions and the mail sends just fine.]

Everything seems to be in order when checking my settings. I finally called Yahoo and spent an hour on the phone with them, including a supervisor (in the background) and they were unable to correct the situation. Yes, since I had called them from their tech support line (I looked it up; did not call anything sent to me) and they worked on my computer trying to fix it. They finally said it was a Thunderbird issue and said I needed to contact Thunderbird.

I am able to send from my phone (Android) using the same cox.net e-mail address. My wife is able to send from her computer using her cox.net via Thunderbird. My wife's incoming mail is IMAP while mine are all POP.

I happen to have several cox.net accounts and get the same SMTP error on all. However, all receive POP mail just fine, but see the next paragraph.

[As an aside (?), I should note that after Yahoo attempted to "fix" the problem, ALL my incoming cox.net mail comes into ALL of my cox.net accounts regardless of which one is addressed.]

I don't even know where to start at this point. Thanks for any help.

Bill

For a few weeks now, sent emails have not been appearing in the "Sent" folder. The recipient receives the email, but I have no confirmation in "Sent" that it was actually sent. It was never a problem.

Attached is a picture of what my account settings looks like. Thunderbird stopped syncing my emails from a gmail account. How do I get it to continue syncing my emails?

Sans aucune raison ni manipulation je n'ai plus de mails dans Thunderbird

J'ai quitté l'application, redémarré mon MacBook et rien n'y change. Quand je vais sur le webmail j'ai bien la totalité de mes mails. Par contre j'avais un dossier local et du coup je n'y ai plus accès non plus

On my iMac, across all thunderbird email accounts, when I click on "New Message", the new window opens up with the Send button and Encrypt button blanked out. To activate the Send button, I have to right click on the Send button, then click on "Customize..." button, then click on "Restore Default Set". Next new message, same drill. This started one day ago and is a pain in the butt. How do I make the Send button live permanently?

I started a monthly donation to Thunderbird a few hours ago and now I'm thinking it may have been a scam. Not sure, and I have sent an email to your donation email about this. Since I made that donation (and maybe this is a coincidence), I am not able to send any emails. I can compose an email, but there is no "send" button anymore. Can you help me with this? Thank you very much.

Bug report 15 Aug. 2026

The disappearing emails.

It took me a while to find out what was going on. My friend said some of his Sent mail was nowhere to be found. After searching for it in a 'wrong' place it does not exist. Sending to the same recipient and again it just disappears. Simplifying the mail down to just address and the word "test", it still disappears. No combination of a Thunderbird search nor an Everything search finds anything. No return error message from this provider nor the recipients.

This address is for the local electricity board, other mails to other departments

go through correctly and are found in the Sent email directory.

A careful inspection of the contact information shows this is the only department

without a "Shown Name" it only has an email address filled in.

Entering a Name for this contact solves the problem, it now shows up in the Sent

folder and is easily searchable.

I hope this explanation helps some one else with a 'Houdini' email.

My Thunderbird email account no longer lets me send out messages. I get a message error

  QUOTE____

Sending of message failed. An error occurred while sending mail. The mail server has responded. Message contains bare CR and is violating 822.bis section 2.3. Please check the message and try again.

But I am able to receive messages.

Can anyone help. Thanks in advance!!

bob.fannon

Feb 14, 2026, 13:01 CST

I have used Thunderbird for a number of years with Plusnet (using POP settings) in the UK. However, Plusnet has transferred their support to a company called Greenby who have made a hash of it and offer very poor support. So, I want to use Outlook as the mail server but I am unable to send any messages via Thunderbird to the Outlook server. I can however download messages with no problems. The error message I get is :- Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.office365.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'

My default Outgoing Sever settings are :- Server Name : smtp.office365.com Port: 587 User Name: bob.fannon@outlook.com Authentication method: OAuth2 Connection Security: STARTTLS

I have tried deleting the Thunderbird account and re-creating it but still got the same result. I also tried to use my old Icloud account ( having first setup my App Specific password) but got the same result.

Hi David This is the last attempt I did but it failed. Enclosed is the screen shot you have asked for. Keep in mind my WIN 10 has 64 Bit but the last update from Thunderbird was 32 Bit

Heinz

Hello,

I have been using Thunderbird for years without issue, but three days ago, I started having issues.

Now, I don't receive emails when I open Thunderbird. If I delete my password and re-sign in, I receive emails, but cannot send them. Trying to send an email makes Thunderbird ask me to sign in again.

I have two email accounts that I use with Thunderbird. Both accounts have this issue. I have this issue regardless of the network I'm in (work, cell hotspot, or home).

Things I have tried:

• Verified that my IMAP and SMTP settings match the guidance from email servers.
• Verified that my computer firewall is not blocking email.
• Tried connecting on different networks (so different ISPs)
• Deleted and re-entered passwords for each account

Here my current server configuration:

• Email 1 (@gmail.com)

 * Server Name: imap.gmail.com
 * Port: 993
 * Connection Security: SSL/TLS
 * Authentication Method: OAuth2

• Email 1 Outgoing Server:

 * Server Name: smpt.gmail.com
 * Port: 465
 * Authentication Method: OAuth2
 * Connection Security SSL/TLS

• Email 2 (@[university].edu)

 * Server Name: outlook.office365.com
 * Port: 993
 * Connection Security: SSL/TLS
 * Authentication Method: OAuth2

• Email 2 Outgoing Server:

 * Server Name: smtp.office365.com
 * Port: 587
 * Authentication Method: OAuth2
 * Connection Security SSL/TLS

I will greatly appreciate any help you can provide!

I've never had a problem before but suddenly I'm getting an error when I try to log into one of my accounts telling me "The STAT command did not succeed. Error getting message number and sizes. Mail server pop.gmail.com responded [AUTH] invalid credentials. Why is this happening now?

I have 4 other accounts on Thunderbird and this is the only one that has started giving me problems.

Setting up Thunderbird for the first time so I can use Thunderbird as "aggregator" for all types of email (incl POP3) on both PC and android tablet. It is working for my Gmail account but not for my POP3 account with Roadrunner (aka Spectrum, aka Charter). The POP3 account is most important and I have 2 more addresses there that I also need to monitor. In the settings section for the roadrunner account there is a server test which seems to work but no email shows up in that account in Thunderbird. I am still getting new email directly in the Spectrum setup that I always use. Google AI thinks my setup should work. How should I proceed? Obviously contacting Spectrum is the easy answer but I thought maybe someone easier to contact would know a likely cause. Thanks

When i attempt to retrieve my email I get the following message at the top of my screen, "The certificate for POP3.pangia.biz expired of 8/13/26. How do I renew it? My email address is jahoagy@signalpeak.net. Thank you John Hoagland.