At https://mail.mozilla.org/pipermail/tb-planning/2020-October/008030.html this PR is called “Improved account setup flow: TB should guide the user through an account setup process that sets up all the services they will need.”
For the account setup:
• Bug 1667608 asks for an account setup process (e.g. for address firstname.lastname@example.org) that setups CalDAV and CardDAV services, but does not setup SMTP/IMAP services
• For the cases, where the user setups WebDAV derivative and Email at the same time (thus possibly always), the setup process shall in the first step ask for the email address, get the DAV:displayname for the principal over WebDAV (current-user-principal) and on the second step propose its value under „Your name”, so that the user does not have to enter it manually.
• For CalDAV+SMTP integrated setup, TB shall get the CalDAV:calendar-user-address-set from the server and create email aliases based on it