Thunderbird Community Forum

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

After returning from a 6 day vacation, my wife attempted to download email from her Yahoo email account. There are nearly 200 messages that have piled up but they aren't moving. I've uninstalled and re-installed TB. I've uninstalled and reinstalled the app password in Yahoo. There is no problem with accessing the email via any web browser. I spent 49 minutes on a tech support call with Yahoo and they have said the problem is with TB because they repeated the same steps I have. I checked firewall settings and the only antivirus program on the computer is Malware Bytes and it's not running in the background. The version of TB is the most recent as of yesterday. I don't see any sketchy looking emails in the web version of Yahoo Mail when it's opened. It's set up as a POP3 account and has been since Cox Internet gave their email over to Yahoo. I'd appreciate any assistance in resolving this because it's currently above my pay grade and tech support at Yahoo.

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?

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.

hello: for several weeks, each time I tried to add another account back to Thunderbird, MS asked for the verification, and after I added it to link to their server, it kept telling me, "Help us beat the robot," and nothing else happened; the screen stayed blank. I am unable to see any further command. If it is being done using Windows, often you may see holding down the space bar or solving a puzzle to gain access. When it comes to Linux, I ran into this issue.

This is strange! Maybe it is trying to stop me from using this account on this platform to get all my mail here. I've been using it here for many years and no issues. Please see the attached. Please look into this. Thank you....

Thunderbird running 70-80% CPU with status bar showing. Once status bar is removed this drops. Have noticed some bug reports mentioned Linux but I'm on Windows 10 ESU (up to date). Updated TB to 153.0.3esr but no improvement. Tried troubleshoot mode but no improvement. Also noticed that emails aren't getting moved to the deleted folder from inbox. Checked today and none had been moved for 3 days. I deleted some of the older ones from 'Deleted' and then it did update.

Little thing. None of the sections seemed appropriate. Win 11 153.0.3 (64-bit) In the left-hand panel of Calendar the top left icon of the actual calendar day/week/month matrix is supposed to take you to today (though it's not obvious by the icon which changed a few versions back). When first coming to it after a restart (hibernation mostly in my case) it doesn't move the highlighted day. I have to click first on any other day, then click the icon for it to go to today.

I am using Thunderbird Meadow.

Is it possible to send emails without a subject, other than getting the warning dialogue box.

It would be very useful.

Thank you

1. 1. Thunderbird connects to my IMAP/SMTP server but neither receives nor sends mail

I am having a problem with Thunderbird on Windows with a custom-domain email account hosted by Advika Web.

1. 1. 1. Account

Email address: `connect@synergyappstudio.com`

Mail hosting provider: Advika Web

The mailbox and password are confirmed to be valid because I can successfully log in to the provider's webmail using the same email address and password.

1. 1. 1. Server settings provided by the hosting provider

Incoming IMAP:

• Server: `mail.synergyappstudio.com`
• Port: `993`
• Connection security: SSL/TLS
• Authentication: Normal password
• Username: `connect@synergyappstudio.com`

Outgoing SMTP:

• Server: `mail.synergyappstudio.com`
• Port: `465`
• Connection security: SSL/TLS
• Authentication: Normal password
• Username: `connect@synergyappstudio.com`

1. 1. 1. What happens in Thunderbird

Thunderbird shows:

> Connected to mail.synergyappstudio.com

However, incoming messages are not downloaded and outgoing messages cannot be sent.

The SMTP error I received was:

> The connection to Outgoing server (SMTP) mail.synergyappstudio.com timed out.

1. 1. 1. Connectivity tests

I tested the server from Windows PowerShell.

Port 993:

`Test-NetConnection mail.synergyappstudio.com -Port 993`

Result:

> RemoteAddress: 103.69.196.146 > RemotePort: 993 > TcpTestSucceeded: True

Port 465:

`Test-NetConnection mail.synergyappstudio.com -Port 465`

Result:

> RemoteAddress: 103.69.196.146 > RemotePort: 465 > TcpTestSucceeded: True

Therefore, both TCP ports are reachable from my computer.

1. 1. 1. TLS tests

I also tested the actual TLS handshake rather than just TCP connectivity.

TLS 1.2 against IMAP 993 failed with:

> Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

TLS 1.0 against IMAP 993 produced the same result:

> Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

I also tested the TLS handshake against SMTP 465 and received the same "connection was forcibly closed by the remote host" result.

1. 1. 1. Comparison with Outlook

There is an important comparison:

The same mailbox **successfully connects and authenticates in Classic Outlook** using the same server and credentials.

However, I am using Microsoft Office Home & Student, so Classic Outlook is not available to me as a practical permanent solution for this business email account.

Microsoft's **New Outlook** also fails to add the account and displays:

> Sign in failed. Please try again in a few minutes. You may need an app password.

The mailbox does not use Microsoft 365 authentication. It is a conventional hosting-provider IMAP/SMTP mailbox.

1. 1. 1. Thunderbird troubleshooting already attempted

I have:

• Confirmed the password works through webmail.
• Confirmed the supplied IMAP/SMTP server names.
• Confirmed ports 993 and 465 are reachable.
• Confirmed SSL/TLS settings.
• Used Normal Password authentication.
• Used the full email address as the username.
• Tried Thunderbird with the supplied IMAP/SMTP settings.
• Reduced **Maximum number of server connections to cache** from the default 5 to 3 and then to 1. This did not resolve the problem.
• Restarted Thunderbird after changing the connection-cache setting.
• Tried Thunderbird's connection logging, but the generated log files remained 0 KB, so no useful log was produced.

1. 1. 1. Additional observation

Thunderbird displays "Connected to mail.synergyappstudio.com", but the account does not actually synchronize incoming mail.

The provider's webmail works normally, and Classic Outlook works with the same mailbox.

1. 1. 1. What I would like help determining

Could you please help determine whether this is:

1. A Thunderbird IMAP/SMTP compatibility issue with this particular mail server; 2. A TLS negotiation issue; 3. A Thunderbird configuration/profile issue; 4. A Windows/security-software interaction; or 5. Something specific to the mail server's IMAP/SMTP implementation?

In particular, I would like to understand why Thunderbird can establish the connection but cannot complete the IMAP/SMTP communication, while Classic Outlook works with the same server, ports and credentials.

I can provide Thunderbird version information, Troubleshooting Information, screenshots of the account configuration, or any additional diagnostic information you need.

Since some time my standard number of print copies in Thunderbird has changed from 1 into 2. I have to adapt this number each time I print. How can I change this back?

Hi.

Just had a not requested update to 153 esr, which in itself is generally fine, with a small exception.

The windows min, max and close buttons all come up with a code.

Probably just some weird setup I have but any ideas will be welcome.

I use userChrome.css to give a background colour, so maybe the ID of each has changes for any css

1. titlebar-min{height:1.66em; background:#00b !important}
2. titlebar-max{height:1.66em; background:#090 !important}
3. titlebar-close{height:1.66em; background:#d00 !important}

but I don't see how that would effect the actual bare icon

Thank you

I usually browse my emails using saved search folders. Messages in these search folders are losing their tags. I tag the messages, and when I browse them later, the tags are gone. The same happens in regular folders and subfolders. If I browse the regular folders and tag messages while visualizing these folders, the same happens again. Any guesses?

My e-mail stopped downloading. It was working fine, I changed nothing, no error message. It accepts my password, cycles through it's process, then quits without downloading anything. Sending still seems to work.

We did relocate from home to my folks' in-between, but I've never had issues at their place before, and otherwise my connection to their wireless works fine.

I'm on TBird 153.0.2esr after a recent update. On previous versions the "Get Messages" button in the top left side of the menu's was working fine. When the button was selected, an update was displayed in the bottom left frame of the window. The update would say something like "Connecting to ..." and the message would be downloaded from the server. Great...

If there were no messages on the server, the update would display "There are no messages on the server". With this current version, I don't see any messages in the lower left frame of the window.

This is a convenient feature of the app, as I like to check the server for messages prior to shutting down. It's also convenient for getting messages with a security code without having to wait for the next scheduled message download. Now I can only assume there are no incoming messages when I push the button and don't see anything in my Inbox.

Dear Mozilla Development Team, Please reinstate this feature for upcoming versions of Thunderbird. Oh, BTW, this is a great app that I use daily for email. I use the calendar as a log book for my daily activities as well as an appointment scheduler. Thanks for your attention.

P.S. I see a new version is available (153.0.3esr) today (8/14/26), so I'll update and see if the same issue occurs.

Ever since last 2 windows updates, thunderbird always asks for passwords and authorization for google calendar...this happens when you restart the computer and when you log out of thunderbird and log back in....this never happened before I uninstalled thunderbird and reinstalled it and it keeps happening is there a fix?