Still the same today, no initial sign in. Has this extra level of security been deleted?

Can't understand why I have yet to had any replies as this is quite a fundamental aspect of the T.Bird system.

So nobody else sees this change?

re : I had then to sign in with my password & then sign in again when sending my first mail of the day. You would be signing in so the account could contact server to check for new mail and also signing in in order to send as that would also contact server. This would only occur if you did not have the passwords saved.

Have you got the passwords saved so it is doing it automatically ? check here: Menu app icon > Options/Preferences > Privacy & Security Under 'Passwords' section click on 'Saved Passwords' button

If you have entries for incoming and smtp then click on 'Show Passwords' button

Thanks that is helpful, but raises other questions. As you suggested I've checked out "Saved Passwords" & found one is set up for IMAP. But it was set up on 14 May 2021 & I did not do this! Is this the reason that I do not have to sign in with password but have to sign in when I send 1st mail of the day? Also how did the "Saved Password" get set? To remove this "Saved Password" do I just select "Remove All" in the Password section, & is this best?

RE: As you suggested I've checked out "Saved Passwords" & found one is set up for IMAP.......Is this the reason that I do not have to sign in with password but have to sign in when I send 1st mail of the day?

Yes: Thunderbird is automatically acecssing the server using that stored password, so that would explain what is going on.

re: But it was set up on 14 May 2021 & I did not do this! These are the only ways a password gets saved. When you enter the password at prompt, the checkbox to remember password was selected (checked). Or the account itself was created on that day and when creating the account the 'Remember password' checkbox was selected.

To remove it: select that imap line and click on 'Remove', click on 'Close' and then restart Thunderbird.

Note: if imap account is using OAuth2 for Authentication Method, then passwords need to be saved and cookies need to be allowed.

Personally, I save all my account passwords as it saves a load of time. When I boot up computer, I have to logon to my User Account using a password just to see the desktop, so if you do not know that 'User Account' password, then you do not get access to the desktop and cannot open and use my Thunderbird profile. It is reasonable protection. I'm not working in an environment surrounded by people and I log out of User account when away from computer anyway as a habit.

Thanks, See what you mean, but I prefer to log in daily. So I've cancelled out the saved password. But I still do not understand how the saved password got there. I've been using T/Bird for years & always signed in at start of a session. Just wonder if the last update somehow did it? Anyway thanks to you I'm a happy bunny now.