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Mac OS Monterey update results in failed sends

Louis de Beaumont
Louis de Beaumont
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Hi, thanks for all your help.

I updated to Mac OS Monterey this evening, and since the update haven't been able to send emails. Receiving emails works fine.

Using gmail server smtp.gmail.com Port: 465 Auth. method: OAuth2 Connection Security: SSL/TLS

I've followed every bit of advice I could find:

  • Setting SMTP auth to normal password (from OAuth2)
  • Deleting saved passwords and reauthenticating with Google, repermitting Thunderbird etc.
  • Turning OS firewall off and trying to send (same 'unknown error' thrown)
  • Reinstalling Thunderbird
  • Setting auth to 'No authentication' fails because Google (and I) require it

I'm assuming it's to do with my OS update, but I could be wrong. Any advice?

Hi, thanks for all your help. I updated to Mac OS Monterey this evening, and since the update haven't been able to send emails. Receiving emails works fine. Using gmail server smtp.gmail.com Port: 465 Auth. method: OAuth2 Connection Security: SSL/TLS I've followed every bit of advice I could find: * Setting SMTP auth to normal password (from OAuth2) * Deleting saved passwords and reauthenticating with Google, repermitting Thunderbird etc. * Turning OS firewall off and trying to send (same 'unknown error' thrown) * Reinstalling Thunderbird * Setting auth to 'No authentication' fails because Google (and I) require it I'm assuming it's to do with my OS update, but I could be wrong. Any advice?

Chosen solution

I have solved the problem. Funny how posting on support boards is part of getting closer to the solution, even if not providing the answer.

My issue was the attached file I was trying to send. Google was flagging it as a security threat; the file was from an old family computer and needed updating (i.e. saving with a modern program).

Possibly Thunderbird would like to note this error message and pass it from Google back thru Thunderbird. (Not to be presumptuous. Great app. Long live Mozilla. Thanks.)

Read this answer in context 👍 0

All Replies (2)

Louis de Beaumont
Louis de Beaumont Question owner
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Also my draft email has synced with the Google servers (i.e. I can see it on mail.google.com), and I can send emails using mail.google.com in browser.

Louis de Beaumont
Louis de Beaumont Question owner
more options

Chosen Solution

I have solved the problem. Funny how posting on support boards is part of getting closer to the solution, even if not providing the answer.

My issue was the attached file I was trying to send. Google was flagging it as a security threat; the file was from an old family computer and needed updating (i.e. saving with a modern program).

Possibly Thunderbird would like to note this error message and pass it from Google back thru Thunderbird. (Not to be presumptuous. Great app. Long live Mozilla. Thanks.)