Optional filter for matching emails based on fields. For instance filter results to only include emails whose `SUBJECT` value does `CONTAIN` given match value. An example payload would be `{ matches: [{ field: 'SUBJECT', should: 'CONTAIN', value: 'Welcome' }] }`. You can also pass conditions such as `HAS_ATTACHMENT`. If you wish to extract regex matches inside the email content see the `getEmailContentMatch` method in the EmailController.