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As of 2 days ago I am unable to send emails using my Thunderbird client.

  • 7 replies
  • 4 have this problem
  • 75 views
  • Last reply by david

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I have Thunderbird 115.4.1 as of 2 days ago I have been unable to send any emails. I have Spectrum as my ISP and the error message I get is:

Sending of the message failed. An error occurred while sending mail. The mail server responded: <lzweig1@san.rr.com> sender rejected. The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out - 1500. Please verify that your email address is correct in your account settings and try again.

None of my settings have changed in years, and all of a sudden I cannot send any emails. I have talked to Spectrum and verified that all my settings are correct. All they tell me is that I need to contact Thunderbird support. I can receive emails just fine, just not send any from any of my Spectrum accounts. If I use the Spectrum webmail service everything is fine. But all my emails and address book are in Thunderbird and I would like to continue to use Thunderbird as my default email client.

Please help, Larry

I have Thunderbird 115.4.1 as of 2 days ago I have been unable to send any emails. I have Spectrum as my ISP and the error message I get is: Sending of the message failed. An error occurred while sending mail. The mail server responded: <lzweig1@san.rr.com> sender rejected. The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out - 1500. Please verify that your email address is correct in your account settings and try again. None of my settings have changed in years, and all of a sudden I cannot send any emails. I have talked to Spectrum and verified that all my settings are correct. All they tell me is that I need to contact Thunderbird support. I can receive emails just fine, just not send any from any of my Spectrum accounts. If I use the Spectrum webmail service everything is fine. But all my emails and address book are in Thunderbird and I would like to continue to use Thunderbird as my default email client. Please help, Larry

All Replies (7)

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Would you please post a screenshot of your SMTP server settings pane and one of your account setting pane that shows email address? That may help.

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Here are the SMTP settings. There have been no changes to these in years.

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Not that one, the account pane. It will have email address near the top and the bottom line specifies the SMTP server being used. I also offer the suggestion to use a secure communications approach, as you are sending password unencrypted.

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This is the only "account settings" pane I could find. I hope it helps you help me. Thanks, L

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It appears that you have four email accounts, but only one SMTP server. You need a separate server set up for each of the accounts. That seems to be the core of your problem. I suggest adding a description for each so that when you check the account settings, you will be positive on which server is assigned to an account.

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Nothing has changed regarding servers/accounts/settings for years. Was there some Thunderbird upgrade in the last week? If I uninstall TB and reinstall it how can I save my existing emails and address book?

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What has changed in recent months is that email providers are tightening up on security. When a server is asked to process an email from xxx@com and the smtp server says if from zzz@com, the receiving server suspects spam and rejects the message. I have been seeing this issue for past several months. I have also seen a rise in demanding secure connections, such as ssl/tls or starttls, as appropriate. Do not uninstall TB. Just create an smtp server for each account and give a unique description so when you click the account page to select the smtp server, you will be assured that you're connecting to the right one.