Telus says you go to
mail.google.com (Gmail's webmail address) to access
your migrated account via webmail. Telus says if you use the old webmail
address, you will still be redirected to Gmail's webmail address. After
migration, what you have is a Google account, although the primary alias
is still your old Telus address. Everything at this point going forward
is Gmail. As soon as you understand this, the faster you'll get things
working right. Google is getting rid of the "less secure apps access"
provision. Moving forward, you shouldn't have to lower the security of
your new Gmail account just to grant Thunderbird access. Use an
app-specific password for that, but since Gmail's OAuth2 is built into
Tbird, there is no point in using an app-specific password in Tbird.
>
> All's accepted but logging in after re-staritng TB produces rejection.
>
> So I go back to authentication by 'normal password'... still SSL...
> tell my Telus-related Google account to allow an insecure app... and
> everything works semi-perfectly.. with resumed security warning in the
> account!
>
Telus says, disable the old Telus account in Tbird, then setup the new
Google powered account as a new account in Tbird, and use OAuth2 with
gmail servers. Did you open the links I posted in my earlier reply?
Also, in Tbird, open the password manager (Saved Passwords) and remove
the entries for the old (Telus) servers. The only entries that should be
saved and used are for working accounts. Also, if you have disallowed
cookies in Tbird, you need to allow them for OAuth2 to work, otherwise
you will have to perform the OAuth2 process on each restart of Tbird.