Thunderbird has always stored a separate password for incoming and outgoing servers.

1. Have you tried clicking on the save option in the dialog asking for a password?
2. What is your mail provider?

Thanks for the reply Re 1 the dialog box does not have a save option other than save to a password manager. Re 2 my mail provider is Telstra through their Bigpond app

1. That is the option. Save it so you are not asked all the time to provide it. It has been the same password manager in Thunderbird since day one. 2. While it is off topic, you have my commiserations. I am finally getting rid of them after 40 years as a landline customer. Viva Starlink for us bushies.