Domain ID (can be obtained from the GetMX management backend or through the /v1/domain/list endpoint; the 'id' field is the 'domain_id')
Example:
12345678
group_pay_id
string
optional
Filter by group_pay_id (group_pay_id can be obtained from the GetMX backend or through the /v1/group-pay/list endpoint, with the 'id' field corresponding to 'group_pay_id').