Thunderbird and BT email: outgoing server error message

[green_onions]

Using latest Thunderbird (115.8.1 ) email client on a Mac desktop.  Incoming emails are received OK, but outgoing emails will not send since the last few days, and are generating the following error message:

"Sending of the message failed. An error occurred while sending mail. The mail server responded: 

We're sorry, but we can't send your email.  Either the subject matter, a link, or an attachment potentially contains spam, or phishing or malware.  Please check or edit your message and try sending it again. (6-1-3-2) ID (65A567CD064875D1)."

The emails contain no links, no attachments, and are newly generated emails. SMTP server settings have not changed as as listed by BT (port 465, etc). I have switched off VPN and Firewall, and this makes no difference, still the same error message. Emails sent on a Mac laptop , using Mail email client, are sending fine. Does anyone have any suggestions? Thanks.

[licquorice]

Check that Thunderbird has the correct SMTP password.

See the last post on this thread https://community.bt.com/t5/Email/Thunderbird-fails-to-send-to-BT-Email/td-p/2231304/page/2

Although the thread is nearly 2 years old, there was a recent post this week.

[green_onions · Accepted solution]

Thanks for the response.  The SMTP password hasn't changed and was working fine until recently , and works fine currently as stated on a laptop, the problem is with sending emails from the desktop. I suspect that for whatever reason the Thunderbird app on the desktop has become corrupted - I decided to re-install Thunderbird, and with exactly the same settings and password as previously I'm able to now send emails from the desktop with no issues .  This thread can now be closed.