Settings › Sharing opens with two switches for the whole server, and a
tenant's page carries the same two for that organization (multi-account
spec, MA-C, MA-13): people may share their own mail folders, and people
may add other accounts to the webmail. Turning mail sharing off refuses
new shares and stops honoring the old ones until it is on again; groups
and shared mailboxes keep working. A tenant can only be stricter: a
switch the server has off shows off on the tenant's page and can't be
turned on there. An older server without inbuxa:SharingPolicy shows
nothing.
Changing the server's needs sysSharingUpdate; a tenant's, the tenant's
domain permissions, as its legacy protocols switch does. Nine new
strings, in en.json. typecheck, lint, i18n:check, vitest and build
pass.