All Products Community Forum

I have Comcast as my internet service provider. I use Thunderbird to download a copy of my e-mails from their server and send e-mails out through their server. Until about a month ago, Thunderbird, which I used for many years will not send my e-mails but will still allow me to receive my e-mails. When I try to send an e-mail, I get an error message that says Login to server smtp.comcast.net with username (then my e-mail address).net failed. I had read on Google that Thunderbird was having some trouble and one of the fixes was to uninstall Thunderbird and reinstall it. Also, to check my settings on my computer which I did and nothing has worked. When The message doesn't go through, after this failure message, I then get this message "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)'. I tried changing my password and it did not help. I also contacted the Comcast security team which was able to help me with a previous Thunderbird issue but not this one. They said the problem was with Thunderbird this time. Can anybody assist me with this please?

Emails received in reply seem to couple themselves under the original sent email. How do I tell Thunderbird to treat them as separate, and stored them in my inbox as a separate individual email. Thank for your advice. Kanga85

I've installed the latest desktop version of Thunderbird to evaluate. The signature is added only for new messages and not included when replying or forwarding a message. I've tested the signature with both plain text and html signature - both doesn't work as expected. I've also tried pasting the html code in the input field and attaching it as a file. Is this an intentional omission of functionality or I'm I missing something? I'm attaching my account settings interface.

I have been using Thunderbird for years and have never had any problems; unfortunately, from few days, every time I try to download my mail, thunderbird starts downloading all my 15,000 emails, even though they have already been downloaded and read. I am desperate... I don't know what to do. Please help me... thanks!

I am using ThunderBird, and when I mistakenly sent to the wrong recipient, I did not receive an email indicating a sending error (bounce). It is not in my spam folder or trash folder. What should I do to receive emails indicating a sending error?

Running version 128.10.1esr. This version and the two previous mark 50% of incoming emails as ***SPAM*** and put in Junk folder. Turned off SpamAssasin. Marked all as not junk. Added all addresses to address books. Nothing fixes this problem. There is no way to contact Mozilla directly for a solution so I am posting here. No, this is not email coming from a third party account like Gmail. No, it's not inheriting spam designations from another server. This is broken junk settings on the previous two versions of Thunderbird. Mozilla, please fix this.

The Help Article explains how to create a new email distribution list-- In address book, select "File", then "New" then "mailing list". in the drop down box for "New" there is no listing for "mailing list". I keep my version up to date but I would like to know why I don't see "mailing List" so I can click on it and create a new email distribution list. Your site tells me how to do this but it doesn't match what I see when I follow the instructions. Please advise.

If this is not possible consider it a feature request.

It would be great if we could set a list of email addresses (or have a checkbox in each address book contact) that would specify which emails to always send receipts to.

Communications have various degrees of importance. Some people you communicate with may be related to a specific project, for which you may or may not need return receipts.

On top of that, some people are busier than others. Someone may be receiving 10 times more emails per day than someone else. For them it's preferable to make sure the message you sent didn't slip through the cracks or have proof on your side that they received it. But for others, it's overkill, not very eco-friendly and clutters your inbox.

Manually specifying whether or not to send a return receipt on every message you send is risky, as you may not always think to do it, and then your important message sits for days or weeks before someone realizes it wasn't read.

Since 5.18.2025 I get a "no message found" in my sent folders and other folders. "Find" will still find the messages and they can be opened, but I can't get the email folders to display. I know they are still there. Version 128.10.2esr. How can I get them to display in the folders?

Everything was fine in 115esr. I think I missed 136 and upgraded to 137, and am now on 138. I have five IMAP accounts. The following behavior happens with all of them and has been occurring since I upgraded (to 137 and 138).

I open Thunderbird and it checks for mail. Inboxes will show new messages. I click on any of the Inboxes with new mail. The spam emails automatically get marked as junk and moved out of inbox, and that happens only after I view that Inbox.

The previous behavior, and what I expect to happen, is that the spam emails would get marked as junk and moved out of Inbox before I view that Inbox. It's odd to have an Inbox show new emails, go to look at the new emails, then watch them get marked as junk and disappear from Inbox. It's like schrodinger's inbox, the act of observing the inbox determines the fate of the spam emails :p

I have noticed a reply to messages made from our phones are not synced with our Thunderbird Desktop. If employee 1 replies to a message from their phone, employee 2 and 3 cannot see their reply. This creates gaps in conversations that negatively affect customer support.

I use the Thunderbird email app on my phone, I am not sure what app others are using.

Is there a setting somewhere I am missing? or is this a bug that needs to be fixed?

Thank you in advance for any help you can provide.