The following are existing preconditions that are reused for the POST method on an Outbox collection.
o DAV
need-privileges [RFC3744]
o CALDAV
supported-calendar-data [RFC4791]
o CALDAV
valid-calendar-data [RFC4791]
o CALDAV
max-resource-size [RFC4791]
The following are new method preconditions for the POST method on an Outbox collection.