Thunderbird for Android problems sending mail via optonline.net began several days ago.
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]
Modified by Karl Schmitt
All Replies (2)
I have moved this question to the Android product section - https://support.mozilla.org/en-US/questions/thunderbird-android
So, I found the debugging mode
Click the three bars in the upper left corner. Click the Gear in the lower left corner. Click the "General settings" gear in the upper left. Click "Debugging". Enable debug logging Enable Log sensitive information
Back out and generate the error.
Go back to the Debugging screen. Click the three dots in the upper right corner. Click "Export logs". Choose a location and Save the log.
That's how I got the log file where I found the snippet below.
Notice how it says "authentication successful" which indicates to me that the ID and Password handshake worked fine. Then it is followed by the error 550 Sender refused.
I'm going to take another shot at optonline tech support with this info. If anyone has any suggestions.... please.
05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-altprdrgo005.altice.prod.cloud.openwave.ai 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-DSN 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-8BITMIME 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-AUTH=LOGIN 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-AUTH LOGIN PLAIN 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250-DELIVERBY 300 05-21 08:37:44.852 6047 6077 V SmtpTransport: SMTP <<< 250 SIZE 104857600 05-21 08:37:44.853 6047 6077 D SmtpTransport: SMTP >>> AUTH PLAIN AGtzY2htaXR0QG9wdG9ubGluZS5uZXQAQmlkNjJLME8yajdGc3FR 05-21 08:37:44.954 6047 6077 V SmtpTransport: SMTP <<< 235 PLAIN authentication successful 05-21 08:37:44.954 6047 6077 D SmtpTransport: SMTP >>> MAIL FROM:<*******@optonline.net> BODY=8BITMIME 05-21 08:37:45.057 6047 6077 V SmtpTransport: SMTP <<< 550 Sender refused 05-21 08:37:45.057 6047 6077 D SmtpTransport: SMTP >>> QUIT
Modified by Karl Schmitt
You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.