When using RPC it seems I can "only" use a user. Same automation via Forms the models are created by OdooBot.
"create_uid": [
1,
"OdooBot"
],
"write_uid": [
4,
"Public user"
],
Models created via RPC:
"create_uid": [
2,
"Administrator"
],
"write_uid": [
2,
"Administrator"
],
So there is send an email by odoo bot. But I also don't find where it defined.