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Been using Thunderbird for Android for many months for the email accounts I have with my ISP [optonline.net]. Several days ago sending of emails began failing. Error messages appearing in my Android Notifications say, "Failed to send some messages" "Sender refused". This is happening on all 4 of the devices my wife and I use. 2 phones and 2 tablets. Optimum is blaming Thunderbird. Thunderbird is still working fine on my Windows computer. It seems that all info regarding turning on Troubleshoot mode is referring to the Windows version as I can't find the "Help" menu item in the Android version anywhere. I have reconfigured the accounts in Thunderbird multiple times. The setup of SMTP always seems to end clean with a message of "Settings saved". It seems to me that Thunderbird is getting some error code from my ISPs mail server and I am hoping to have some more info to share with their tech support. The version if Thunderbird for Mobile we are on now is 9. I noticed that version 9 was just released on 5/5/2025. Not sure when exactly version 9 was pulled down to my devices. My phone is Android version 10. My tablet is Android version 14. Both are having the same exact issue. Is there a Troubleshoot Mode in the Android Thunderbird app? Is there a log file that could shed some light on the problem? Just tried the Beta version. Same problem. Also tried versions 8.2 and 8.0, Same problem. I still think that it's on Optonline.net but I'm going to need to do their job for them and find the reason it's stopped working. They are just going to blame Thunderbird. [and yeah, I tried K-9 as well]

I went to use Thunderbird mail on my laptop for the first time in ages. I can receive emails but they won't send:

Log in to server SMTP-mail.outlook.com with username x failed Retry - Enter New Password - Cancel

- I entered the current password, which works fine for Thunderbird Mail on my desktop PC, and checked the box use password manager.

Send Message Error: Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com Please check the password and verify the 'Authentication method' in Account Settings | Outgoing server (SMTP)

Server Type: IMAP Mail Server Server Name: imap-mail.outlook.com I CHANGED THIS to outlook.office365.com - to match the server settings on Thunderbird Mail for my desktop PC - and restarted Thunderbird, but the Log in to server failed message displayed again. Port: 993 Default: 993 Connection security: SSL/TLS Authentication method: OAuth2

I trust I have provided sufficient information for you help me. Thank you!

I am unable to send an original email right now with Thunderbird. I realize "original" is not the best descriptor but what I am trying to describe is if I compose an email to another party, Thunderbird tries to send it and immediately returns the message below even if I send the word Test in the subject line and as the one word text message:

Send Message Error Sending of the Message failed An error occurred while sending email. the mail server respnded: [VO-1] Message blocked due to spam content in the message. Please check the messge and try again.

I have tried multiple email recipients with the same results.

However, if I take an email currently in my Inbox and Forward it to another recipient, it sends it with no error.

Thanks for your help. I am sure I have done something I should not have but I cannot think of what it was.

Mike Black

I have setup Thunderbird to check for e-mail each 30 minutes. But I never get any notifications of any new mails :-( And mails are only downloaded when I start the app and swipe down. Folders are setup to sync (but "push" is not enabled). Power settings are set to "Optimized" (works for all other apps that check for things).

When i have read a incoming email the next time i open my email account the email is gone and i cannot find it anywhere... why... i have check my setting Regards Ed

Group contacts have been established and the group is listed in the Address page. An email is prepared and the group name is inserted in the bcc slot. An x appears to the left of the group name. The Send button is grayed out and the email can't be sent. What is the problem?

Hi,

Unable to send email messages. Receiving "Add Security Exception" and Send Message Error "Sending of the message failed. Peer's Certificate is not recognized. The configuration related to smtpauth.earthlink.net must be corrected." I have checked the account settings and they appear to match that of the email earthlink server settings instruction page (https://help.earthlink.net/portal/en/kb/articles/email-server-settings) for POP3.

Help Please! Thank you! Suz

Good afternoon, dear friends. Thanks for the awesome program for the android version, I use it on my computer too. Can you tell me how to set the frequency of checking emails more often than the 15-minute interval? In other android mail clients, emails arrive almost immediately, within 5-10 seconds, but here the verification interval is very long, and manual verification is such a thing. How do I set it up?

Beginning on May 19,2025 my email will no longer download from centurylink to my Thunderbird program/account. I've tried talking to both centurylink and brightspeed that took over centurylink. They were completely clueless.

bonsoir, depuis quelques mois je ne peux plus envoyer de mails avec thunderbird, orange m'assure que le serveur SMTP est fontionnel. merci de votre aide. Marie Bordet

I'm having an e-mail emergency, and will be very grateful for any assistance. Running TB 128.12.0esr (32-bit) on a 64-bit Win10 PC.

Earlier today, Thunderbird stopped sending or receiving via my main account, on an Earthlink-hosted domain that I own. Turned out that I can still send from accounts on two other domains, one a shared-hosting domain that I own; the other is Verizon/AOL. But I cannot seem to download from any of the three domains.

I checked all the SMTP and POP settings, which worked a few hours ago and have not changed. Restarted Thunderbird several times, inlcusing in safe mode, and rebooted the PC twice. Clicking "Get Messages" - globally or by account - does nothing. The thin blue "working" bar at lower right keeps scrolling, even if I press the Stop button.

I would prefer not to mess around with setting up new profiles and all. Can anyone here please suggest anything less complicated and risky that might get mail working again?

THANKS in advance!

Ich nutze Thunderbird auf dem PC ohne Probleme mit fünf Mailadressen. Jetzt habe ich die App Version auf mein Android Smartphone geladen mit dem Barcodescanner. Ich kann eMails versenden aber ich empfange auf keiner der Mailadressen eine Nachricht über die App Version. Auf der PC Version kommen die Nachrichten an.

Translation: I use Thunderbird on my PC with five email addresses without any problems. I've now downloaded the app version to my Android smartphone with the barcode scanner. I can send emails, but I'm not receiving any messages from the app version at any of the email addresses. Messages arrive on the PC version.

I recently received an email from MemberClicks, an email distribution service associated with an organization that I am a member of. I get these periodically and they are always fine. I usually have to click at the top of the email to say "allow content." This current email did not provide that option and it has no observable content. I get a footer, grayed out that says "This email was sent to eberger@compuserve.com by nhcaoffice@hearingconservation.org National Hearing Conservation Association • P.O. Box 3406, 7173 South Havana Street, Suite 600, Centennial, Colorado 80112, United States Remove My Email or Manage Preferences • Privacy Policy Powered by MemberClicks"

If I go to forward the email or reply to the email, when the email opens up that I will be editing and sending, it briefly displays for about 1 s, the content of the email that was not present. I just had the organization resend the email to another account and this time the same problem occurred. However, I was carefully observing and when I first opened it the content was there for 1 s and then disappeared. I was not given any option to allow content.

This has not happened in the past with this provider. Thoughts?

I am running 128.11.0esr(64 bit)

I'm using Thunderbird 102.15.1 on kubuntu. With previous versions I could set up an automatic filter to move emails to defined folders depending on various criteria. How do I do this with this version? Thanks Hugh Grant

My Thunderbird email works fine except when trying to send emails to someone with an Outlook account. The emails keep bouncing back undelivered.

Any ideas please