Thunderbird Community Forum

I get this message when I try to send emails Sending of message failed. An error occurred while sending mail. The mail server responded: mf-505: Sender Policy - Relay Denied. Please verify that your email address is correct in your account settings and try again. How to I find out this information

Yesterday I found that I can't send mail using Yahoo.ca. I was able to get my wife's computer working by sending an email. A message came on the browser and I logged in to Yahoo. She can now send email. When I tried the same thing on my computer, I get a message "No apps available". I have spent hours trying and can't get around the message. The simplest test is as follows:

• create a new profile, and open the new profile
• enter my name and email address, and continue
• I get a message "Configuration found in Mozilla ISPDB." It uses SSL/TLS and Oauth2
• I hit next. Yahoo opens a page in my browser to log in. I enter the password and the security code sent by text
• The browser sends a message to allow an app. When I allow it the message "No apps available" appears as shown.

The release notes on Thunderbird are Version 153.0 | Released July 21, 2026 For now, I can use a second account on gmx.com to send mail, but prefer to use Yahoo when it works. Any suggestions?

I have two domain accounts; crumpcorp.com and dannycrump.com with GoDaddy. I have two E-mail accounts; [redacted] @crumpcorp.com and [redacted] @dannycrump.com. I use Thunderbird desktop Email. Thunderbird has the ability of use filters to perform automatic actions on messages received. One of the filters is “Forward Message To”. Unfortunately, attempting to forward messages fails. Thunderbird displays the following message:

Sending of the message failed. An error occurred while sending mail. The mail server responded: Request failed; Mailbox unavailable. Please verify that your email address is correct in your account settings and try again.

Please help with this issue.

Please respond to [redacted from community support forum] @dannycrump.com

I have a rather intriguing issue with the message editor which isn't a problem but puzzles me.

I monitor a number of email accounts. When compiling a message using one particular sending account the line spacing in the editor is reduced, as in the second attached image. If I use any of the other accounts it is correct, as in the first image . In each case the line spacing of the message that is actually sent is correct.

It's obviously not a big issue, but I'm struggling to understand how the editor can change depending on the sender account. Any ideas?

I put emails from my Inbox into the delete box. After a while I delete these but I have just found that they remail in the All Mail Box. How do I delete these emails from my acccount on Thunderbird? They do appear in my online Gmail account as far as I can see.

I am unable to access my mails on Greenby with Thunderbird and I suspect the password is incorrect. I can read my mails on the Greenby server and know the necessary password but cannot work out how to enter this into Thunderbird! As I am no expert, a simple guide would be most appreciated! Thanks in advance. Roy

How to avoid: Sending of the message failed. An error occurred while sending mail. The mail server responded: message rejected .

AUP#SNDR. Please check the message and try again.

No matter how large or small the Thunderbird window is, I can't see all 3 of the Address Book columns without expanding the window to take up the entire laptop screen. The column width seem to be locked in at a pre-set number of pixels. I've tried to grab the edges of the columns to reduce their width, but they don't seem to be active. What I would really like would be for the Book to adjust to the Thunderbird window's width, or at least let me scroll between the columns. As it is, I can't view or edit the entry details of a individual listing in my Book without greatly enlarging the whole window.

Any ideas on changing these column widths would be appreciated. I've got Windows 11, and TB version 140.13.0esr (64-bit).

Thanks, Grasses

"The STAT command did not succeed. Error getting message number and sizes. Mail server pop.gmail.com responded (SYS/PERM) Your account is not enabled for POP access. Please visit your Gmail settings page and enable your account for POP access."

I am running Thunderbird on a new Windows 11 laptop. When I download new messages and try and open them my laptop locks up. Anyone else have this problem? Thanks Dave

I am trying to switch from the ESR channel to the release channel. I have Thunderbird 143.13.0esr and am trying to upgrade to 153 (not ESR). When I upgraded, Thunderbird could no longer find the inbox for my primary email and I had to restore both Thunderbird 143.13.0esr and my email library from my Time Machine backup.

I am seeking advice on how to do some cleanup of an inbox anomaly so that I can install 153 without losing my inbox.

Details follow:

My primary email account has had an oddity in Thunderbird for years in which I have two inboxes: an active one with lots of email messages as well as subfolders, and an inactive one which is empty and no subfolders. I have tried deleting the inactive one by selecting it in the sidebar and choosing File, Delete folder, but that command is gray.

By poking around in my Library, Thunderbird, my profile, Mail, my pop account of interest, I discovered the inactive inbox is named Inbox and has only two files, "Inbox" and "Inbox.msf". The active inbox is named "Inbox prev" and has these files: "Inbox prev", "Inbox prev.msf", and a folder "Inbox prev.sbd" which has a bunch of files and more subfolders. All of my four email accounts have multiple folders and subfolders, but I was able to identify both my primary email account and my active inbox from various folder names that were unique to that account and inbox.

Today I followed the following procedure:

1. Quit Thunderbird (and all other apps) 2. Force a Time Machine backup 3. Download Thunderbird 153 for English, US 4. Verify the SHA hash 5. Install Thunderbird 6. Verify the signature 7. Launch Thunderbird

Both my active and inactive inboxes in my primary email account were gone from the Thunderbird interface. I checked my library and the files appear to still be there.

I proceeded with the following remediation:

8. Restore Thunderbird 143.13.0esr from Time Machine, replacing the 153 version 9. Restore the Thunderbird library folder from Time Machine

I launched Thunderbird and my inbox has been restored to the UI, but I am on the esr channel and not the desired release channel.

Is there any kind of manual cleanup I can do to get rid of the inactive inbox, rename the active inbox from Inbox prev to Inbox, and then re-upgrade to 153?

I can see that there has been a reply or a messages was forwarded and when I right click for the menu "Open" may not even appear at times. When it does appear "Open in Conversation" is not always presented as an option even though there has clearly been conversation as I can locate reply's in the Sent folder. Sometimes it's there but when selected it opens a tab that only shows the email and none of the conversations. It's hit and miss and I can find no rhyme or reason. Any help would be greatly appreciated. Also, I would love to Testflight Thunderbird on Apple. Thanks, Sue

It's very odd. Normally moving an email, say from the Inbox to the relevant year's archive, takes "no time at all".

Which is true for all the mailboxes shown on the attached screenshot, EXCEPT for the four at the bottom. Moving even one message from Inbox to Yiddish can take ten seconds or longer (with the dreaded "Not Responding" occasionally). Moving something in the opposite direction is also screwy, only from those four.

I had thought that it was because they're rather large. This first started when there were just Yiddish and MSW, and I split off most of the earlier years into the archives shown. To no avail.

It's only an annoyance, but I'm puzzled about how such a thing could happen.

Also very slow tagging or untagging a message just in those mailboxes.

Last week I deleted about 600 emails from the inbox, leaving about 500. I shut down the computer for 5 days then rebooted. TB seemed to start up ok. I deleted the remaining 500 emails. Emptied the trash folder. Tried to pull new emails to the inbox. I usually receive 100 - 200 emails per day but could not receive any this time.

When I get an attachment as a reply in an email it is with tmp file name. It cannot be opened because Thumberfird does not have a file association program, Using libre office with here I cannot find a file association either. Hoping for some help. Thanks in advance. PS. Should the questions be asked in English?