
Announcements
The activity parties need to be lookup (EntitySetName and GUID inside bracket) just like how you set for Regarding and Owner.
e.g.
[
{
"participationtypemask": 1,
"partyid@odata.bind": "systemusers(f2f6dbe4-3716-eb11-a812-000d3a6aa2fd)"
},
{
"participationtypemask": 2,
"partyid@odata.bind": "contacts(541e5816-b930-ec11-b6e6-000d3abaf6bf)"
}
]
If there's no such record with that email xxxxx@gmail.com does not exist in the system, you can send emails to unresolved recipients as in my blog post below.
https://linnzawwin.blogspot.com/2020/06/send-email-to-unresolved-recipients-in.html