# Mailbox protocol (ID 5)
The Mailbox Protocol allows sleepy devices to retrieve messages during a connection to a Gateway. Gateway devices MAY choose to implement the Mailbox Protocol.
# Message structure
Protocol message structure for Request messages:
| Type Header (THdr) 1 byte | Parameter 1 byte | Command specific payload 0-58 bytes |
|---|
Some commands takes a parameter, like "Get message number 1" - here "Get message" is the command and '1' is the parameter.
Protocol message structure for Response messages:
| Type Header (THdr) 1 byte | Status 1 byte | Command specific payload 0-58 bytes |
|---|
All responses contain a return status code. It indicates to the requesting device if the request was a success or not. 0 (zero) is returned if the request was successful otherwise a negative number is returned to indicate the failure code.
# Type Header (THdr)
The Type Header (THdr) is defined as follows:
| Reserved [7:6] | Proprietary extentions [5] | Command [4:1] | Direction [0] |
|---|
The 5-bit Command field is defined in the table below, the direction bit is:
- 0 - Request
- 1 - Reply
# Commands
| Command | Description | Request parameter | Response payload |
|---|---|---|---|
| 0x00 | Reserved | ||
| 0x01 | Create message | Receiver address | Message contents |
| 0x02 | Number of messages | Number of messages (uint8) | |
| 0x03 | Retrieve message N | Message number | Message contents |
| 0x04 | Delete message N | Message number | |
| 0x04 - 0x1F | Reserved |
# Status codes
| Status code | Description |
|---|---|
| 0 | Reserved |
| >0 | Error |