We found that the majority of errors over the past week were
409s from the contact creation endpoint. (At least 30K each day, up to 36K on Saturday.)
It seems your system is attempting to pass an existing
email values to the Create a new contact endpoint. Unlike the Create or update a contact endpoint, the
/contacts/v1/contact endpoint will only attempt to create new contacts, so passing existing email addresses will cause failures.
The team also identified extraneous lookups. For example, these two calls occurred right after each other:
474 12/3/2018, 11:57:23 AM 204 POST /contacts/v1/contact/vid/201776251/profile
476 12/3/2018, 11:57:23 AM 200 GET /contacts/v1/contact/email/scsc.[lastname]@yahoo.com/profile
scsc.[lastname]@yahoo.com is vid
201776251, so you could save half of these types of calls by attempting to update with the Create or update a contact endpoint or, better yet, the batch create or update endpoint.
To reiterate, these calls are using your account's API key and are not caused by any of these integrations.