Thunderbird Community Forum

I have not been able to get my emails today from Charter on my desktop. Everything was working fine yesterday but nothing in coming through today. It looks like it might load, message that it is downloading 1 of 26 and then says nothing to download. I look on Charter website and there are current emails to download but Thunderbird must have a glitch. I have been on the phone with Charter twice, all the settings are correct for incoming and outgoing ports.

I have looked at the settings in Thunderbird and they are correct. I can get the emails on my iPad and iPhone with the Thunderbird app but not the desktop.

Can anyone give me some direction of where to check next?

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.

Coming from https://support.mozilla.org/en-US/kb/cannot-send-messages, and https://support.mozilla.org/en-US/questions/1596545#answer-1837376 (thank you christ1)

Account settings attached. I don't have an active firewall. My email provider is microsoft (outlook) No antivirus installed Linux Mint 22.3 x86_64 Thunderbird 153.0esr

I have confirmed with microsoft support that the ports and such are correct, they claim thunderbird is the problem.

TB suddenly moves messages from inbox to trash automatically without any interaction. Search through the forrum shows that it has been asked for already, see https://support.mozilla.org/en-US/questions/1588804, similar postings can also be found with you search engine.

As described in other postings, the messages are moved from Inbox to trash. When moving them back manually from trash to inbox, they are moved to trash again immediately.

• it happens for the default account only,
• there're no filters at all in TB,
• junk detection is disabled,
• Settings->General Storage is all disabled,
• (account)->Settings->Server Settings has checked "move deleted messages to trash",
• (account)->Settings->Storage is all disabled,
• Inbox->Properties "Repair folder" does not help,
• Inbox->Properties "rules is set to "use account settings" (and greyd out "do not delete messages"),
• exactly same behaviour when starting TB in save mode,
• manually deleting all *.msf files (for inbox) does not help,
• manually deleting xulstore.json does not help,

Additional notes, which are not related to the problem, IMHO:

• IMAP on port 993,
• no other clients anywhere are connected to that account,
• TB configured for more than 10 accounts, more than 500 folders and sub-folders,
• host with > 16GB RAM, TB uses 3GB virt,
• problem observerd in older TB also, at least 13x.x

I'd be happy to debug/trace the problem if someone can give me detailled insructions how to start TB with debugging. Please feel free to ask for about:config settings as they are non-ambiguous and language independent ;-)

Thanks.

Dear Ladies and Gentlemen,

the last few days my new mails didn’t arrive, perhaps because I tried to introduce new digital items. Please tell me how I can use thunderbird to get my mails; perhaps I have to change my settings. I find it strange that this occurs after I did a donation to you….

Regards,

Agnes Haffner

I ran TB in troubleshooting mode and the problem was still there. I deleted the account and created it again but it did not help. I killed TB and restarted, no joy. I rebooted Windows (build 26200.8875), no help. I have a working hotmail account so I compared the Account Settings and Server Settings, they are identical. Both accounts can contact the Mail Server and I get the Certificate ok. I could add the hotmail email account to my Mail app on iPhone and iPad and that worked fine, so seems like a Windows Thunderbird issue. I tried changing the password of the account to the real password but then restarting TB I got an error message: "login.microsoftonline.com needs you to confirm access again to keep syncing with your account. Username: <foo>@hotmail.com". I do not know how to handle that.

The email I thought I’d sent isn’t in my sent folder. I saw it being sent. I also tried restoring the sent items folder, but it didn’t work. What should I do? Is there any risk of it being misused?

I cant receive emails only send them. I receive an error message when starting Thunderbird "the current operation on inbox <my email address> did not succeed"

Assistance with Read Receipt and Delivery Status Notification

Good afternoon,

Thank you for taking the time to read my email.

I have been trying to determine why I do not receive read receipts after selecting Return Receipt and Delivery Status Notification under the Options tab when sending emails. This has been an ongoing issue for more than 10 years.

I am currently using Thunderbird version 152.0 on one computer and 140.10.2 ESR (32-bit) on another. Despite trying numerous settings and troubleshooting steps over the years, I have never been able to receive a read receipt.

I would be truly grateful if you could guide me in the right direction or let me know if there is a setting I may have overlooked. If there are any troubleshooting steps or additional information you need from me, I would be happy to provide it.

Thank you very much for your time and assistance. I sincerely appreciate your help.

Kind regards,

Brenda

New to Thunderbird.

I have added a Gmail account to Thunderbird. I select a message in Inbox, right click > Move To > Local Folder

It seems to work. It creates a copy in Local Folder.

However, a few seconds later, the message reappears in the Inbox. The message in Local Folder is still there, confirming that copy is made successfully.

Also, the message is still in Gmail account when viewed from Google's Gmail. It's clearly working like Copy rather than Move.

This is frustrating. Is it a bug?

E-Mail messages are in Xfinity, but do not come to Mozilla Thunderbird. Not having access to Mozilla email, prevents messages to be sent from Xfinity. I also cannot send messages from web sites. brucelowrey@comcast.net

Thunderbird is not connecting with Xfinity Comcast for sending or receiving emails at gpenkala@comcast.net . This combination was working fine for decades. Last Friday (Jun 12) was the last email I received in Thunderbird. I can view current emails on the Xfinity website, but these are not being transferred to my Thunderbird account anymore, These are the error messages:

"Sending of the message failed.

Unable to authenticate to Outgoing server (SMTP) smtp.comcast.net. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'." "Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: resomta-c2p-555483.sys.comcast.net resomta-c2p-555483.sys.comcast.net Excessive failed authentication, ESMTP server temporarily not available."

Can you tell me what configurations I should be using within Thunderbird for Incoming and Outgoing Servers?

Things have suddenly disappeared. My sent file is gone and I have searched and can't find it. Tonight I went to send an email and the tab for doing that is also missing. I tried uninstalling and reinstalling with no success. What's wrong and how do I fix it?