List Messages
Query
`filter` with `staff` will show only staff messages and `customer` will show only customer messages.
`filter` with `staff` will show only staff messages and `customer` will show only customer messages.
`tag` with string value (comma separated) will return messages belonging to conversations matching specific tags.
`origin` with number value will return messages from a specific origin (see below note on origin values).
`sent_by` with a value matching a known user `email` will return only messages sent by that user.
`sent_by` with a value matching a known user `email` will return only messages sent by that user.
`category` with a string value will return messages from a specific Channel (internally called `category`) matching the `slug` value.
`start_date` and `end_date` (ISO8601 format) will allow filtering of messages by creation date.
`start_date` and `end_date` (ISO8601 format) will allow filtering of messages by creation date.
`include` with the value `original_body` will return an additional `original_body` attribute that is the message's HTML, if present.
`include` with the value `original_body` will return an additional `original_body` attribute that is the message's HTML, if present.
Comma-separated response fields to include.