You might try this: - click settings>privacy&security - click 'saved passwords', then 'show passwords' - then highlight SMTP server row , right-click, select 'edit password'

That may work.

No. Thanks but no. There is no edit button by the way so I amended the blue data, the date changed to today, I closed Thunderbird and the laptop, restarted and still the same issue. In the worst case I’ll probably have to delete from Win11 and download again, but I’ll need the settings to be emailed to me.

I do not understand your response. "No' for what? What edit button? What blue data? What settings need to be emailed?

No your instructions did not work. There was no edit button. The blue data is what you pointed me to in “show password” to change the password. I altered that password entry and it was apparently accepted as the date in that blue line also altered to today’s date. I closed down as I said, restarted both laptop and Thunderbird. It still does not work and the password field I altered is altered and the date remains changed to today. If I delete thunderbird and reinstall, I need smtp Telstra settings … don’t I ?? I’m glad thunderbird is only an infrequently uss backup for me.

Okay, follow the same steps as above, but when highlighting the row with password, delete the entire row. delete also the row with incoming server info. then close and restart Thunderbird. Now, with no password, Thunderbird should prompt for password.

I’ve deleted Thunderbird.

I checked different paths and I am almost certain the problem is external. I won’t give details but suffice to say my ISP is having issues with web mail server (although other domains are OK) and this is reflected in Thunderbird after I changed my email password for privacy and security reasons.

I also note Mozilla is no longer developing Thunderbird according to my searches so I am looking elsewhere.

Thanks from me

Well, your searches are roughly a decade or more old. Thunderbird is in active development and has released over twenty refinements in past four months. See https://www.thunderbird.net/en-US/thunderbird/releases/ The last major update was in June. Good luck in your search for another email client. Postbox is good ($79) and so is TheBat ($59.99).