Sendmux Email Inbox API + Sending

Official

Overview Schema Source Related Servers Discussions Admin

Get Mailbox Profile

mailbox_get_me

Read-onlyIdempotent

Retrieve profile details for the authenticated mailbox to confirm its identity before processing email actions. Optionally target a specific mailbox when multiple are accessible.

Instructions

Use this to identify the authenticated mailbox before acting on mail. It returns profile details for the mailbox key currently in use.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`mailbox_id`	No	Mailbox public ID to target when the credential grants access to more than one mailbox. Omit when the credential is scoped to exactly one mailbox.
`If-None-Match`	No	Weak ETag from a previous response. Returns 304 when unchanged.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.0.12Sep 19, 2026

changedOutput schema / properties / result / allOf

Previous value: -[
-  {
-    "properties": {
-      "meta": {
-        "additionalProperties": {},
-        "properties": {},
-        "type": "object"
-      },
-      "ok": {
-        "enum": [
-          true
-        ],
-        "type": "boolean"
-      }
-    },
-    "required": [
-      "ok",
-      "meta"
-    ],
-    "type": "object"
-  },
-  {
-    "properties": {
-      "data": {
-        "allOf": [
-          {
-            "additionalProperties": false,
-            "properties": {
-              "created_at": {
-                "description": "ISO 8601 creation timestamp",
-                "type": "string"
-              },
-              "display_name": {
-                "description": "Optional display name shown in outbound From headers",
-                "type": [
-                  "string",
-                  "null"
-                ]
-              },
-              "email": {
-                "description": "Mailbox email address (lowercase)",
-                "example": "agent@acme.com",
-                "type": "string"
-              },
-              "id": {
-                "description": "Public ID",
-                "example": "mbx_clxxxxxxxxxxxxxxxxxxxxxxxxx",
-                "type": "string"
-              },
-              "quota_bytes": {
-                "description": "Storage quota in bytes. Current writable tiers are 1 GB, 5 GB, and 50 GB.",
-                "type": [
-                  "integer",
-                  "null"
-                ]
-              },
-              "send_scope": {
-                "additionalProperties": false,
-                "properties": {
-                  "group_public_ids": {
-                    "description": "Delivery group public IDs (only when type=group)",
-                    "items": {
-                      "type": "string"
-                    },
-                    "type": "array"
-                  },
-                  "provider_public_ids": {
-                    "description": "Provider public IDs (only when type=providers)",
-                    "items": {
-                      "type": "string"
-                    },
-                    "type": "array"
-                  },
-                  "type": {
-                    "description": "Outbound routing strategy. `all` lets the mailbox use any team-configured provider; `providers` restricts to the listed provider IDs; `group` routes via a delivery group.",
-                    "enum": [
-                      "all",
-                      "providers",
-                      "group"
-                    ],
-                    "type": "string"
-                  }
-                },
-                "required": [
-                  "type"
-                ],
-                "type": [
-                  "object",
-                  "null"
-                ]
-              },
-              "status": {
-                "description": "active | suspended | deleted",
-                "example": "active",
-                "type": "string"
-              }
-            },
-            "required": [
-              "id",
-              "email",
-              "display_name",
-              "quota_bytes",
-              "send_scope",
-              "status",
-              "created_at"
-            ],
-            "type": "object"
-          },
-          {
-            "additionalProperties": false,
-            "properties": {
-              "quota_used_bytes": {
-                "description": "Live storage usage in bytes. Omitted when usage is temporarily unavailable.",
-                "type": "integer"
-              }
-            },
-            "type": "object"
-          }
-        ]
-      },
-      "meta": {
-        "additionalProperties": false,
-        "properties": {
-          "request_id": {
-            "example": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx",
-            "type": "string"
-          }
-        },
-        "required": [
-          "request_id"
-        ],
-        "type": "object"
-      }
-    },
-    "required": [
-      "data"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "properties": {
+      "meta": {
+        "additionalProperties": {},
+        "properties": {},
+        "type": "object"
+      },
+      "ok": {
+        "enum": [
+          true
+        ],
+        "type": "boolean"
+      }
+    },
+    "required": [
+      "ok",
+      "meta"
+    ],
+    "type": "object"
+  },
+  {
+    "properties": {
+      "data": {
+        "additionalProperties": false,
+        "properties": {
+          "created_at": {
+            "description": "ISO 8601 creation timestamp",
+            "type": "string"
+          },
+          "display_name": {
+            "description": "Optional display name shown in outbound From headers",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "email": {
+            "description": "Mailbox email address (lowercase)",
+            "example": "agent@acme.com",
+            "type": "string"
+          },
+          "id": {
+            "description": "Public ID",
+            "example": "mbx_clxxxxxxxxxxxxxxxxxxxxxxxxx",
+            "type": "string"
+          },
+          "quota_bytes": {
+            "description": "Storage quota in bytes. Current writable tiers are 1 GB, 5 GB, and 50 GB.",
+            "type": [
+              "integer",
+              "null"
+            ]
+          },
+          "quota_used_bytes": {
+            "description": "Live storage usage in bytes. Omitted when usage is temporarily unavailable.",
+            "type": "integer"
+          },
+          "send_scope": {
+            "additionalProperties": false,
+            "properties": {
+              "group_public_ids": {
+                "description": "Delivery group public IDs (only when type=group)",
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "provider_public_ids": {
+                "description": "Provider public IDs (only when type=providers)",
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "type": {
+                "description": "Outbound routing strategy. `all` lets the mailbox use any team-configured provider; `providers` restricts to the listed provider IDs; `group` routes via a delivery group.",
+                "enum": [
+                  "all",
+                  "providers",
+                  "group"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "type"
+            ],
+            "type": [
+              "object",
+              "null"
+            ]
+          },
+          "status": {
+            "description": "active | suspended | deleted",
+            "example": "active",
+            "type": "string"
+          }
+        },
+        "required": [
+          "id",
+          "email",
+          "display_name",
+          "quota_bytes",
+          "send_scope",
+          "status",
+          "created_at"
+        ],
+        "type": "object"
+      },
+      "meta": {
+        "additionalProperties": false,
+        "properties": {
+          "request_id": {
+            "example": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx",
+            "type": "string"
+          }
+        },
+        "required": [
+          "request_id"
+        ],
+        "type": "object"
+      }
+    },
+    "required": [
+      "data"
+    ],
+    "type": "object"
+  }
+]

Changed4 schema fields changedv1.0.8Sep 15, 2026

addedOutput schema / $schema

Added value: +"https://json-schema.org/draft/2020-12/schema"

removedOutput schema / additionalProperties
```
Removed value: -true
```

addedOutput schema / properties

Added value: +{
+  "result": {
+    "allOf": [
+      {
+        "properties": {
+          "meta": {
+            "additionalProperties": {},
+            "properties": {},
+            "type": "object"
+          },
+          "ok": {
+            "enum": [
+              true
+            ],
+            "type": "boolean"
+          }
+        },
+        "required": [
+          "ok",
+          "meta"
+        ],
+        "type": "object"
+      },
+      {
+        "properties": {
+          "data": {
+            "allOf": [
+              {
+                "additionalProperties": false,
+                "properties": {
+                  "created_at": {
+                    "description": "ISO 8601 creation timestamp",
+                    "type": "string"
+                  },
+                  "display_name": {
+                    "description": "Optional display name shown in outbound From headers",
+                    "type": [
+                      "string",
+                      "null"
+                    ]
+                  },
+                  "email": {
+                    "description": "Mailbox email address (lowercase)",
+                    "example": "agent@acme.com",
+                    "type": "string"
+                  },
+                  "id": {
+                    "description": "Public ID",
+                    "example": "mbx_clxxxxxxxxxxxxxxxxxxxxxxxxx",
+                    "type": "string"
+                  },
+                  "quota_bytes": {
+                    "description": "Storage quota in bytes. Current writable tiers are 1 GB, 5 GB, and 50 GB.",
+                    "type": [
+                      "integer",
+                      "null"
+                    ]
+                  },
+                  "send_scope": {
+                    "additionalProperties": false,
+                    "properties": {
+                      "group_public_ids": {
+                        "description": "Delivery group public IDs (only when type=group)",
+                        "items": {
+                          "type": "string"
+                        },
+                        "type": "array"
+                      },
+                      "provider_public_ids": {
+                        "description": "Provider public IDs (only when type=providers)",
+                        "items": {
+                          "type": "string"
+                        },
+                        "type": "array"
+                      },
+                      "type": {
+                        "description": "Outbound routing strategy. `all` lets the mailbox use any team-configured provider; `providers` restricts to the listed provider IDs; `group` routes via a delivery group.",
+                        "enum": [
+                          "all",
+                          "providers",
+                          "group"
+                        ],
+                        "type": "string"
+                      }
+                    },
+                    "required": [
+                      "type"
+                    ],
+                    "type": [
+                      "object",
+                      "null"
+                    ]
+                  },
+                  "status": {
+                    "description": "active | suspended | deleted",
+                    "example": "active",
+                    "type": "string"
+                  }
+                },
+                "required": [
+                  "id",
+                  "email",
+                  "display_name",
+                  "quota_bytes",
+                  "send_scope",
+                  "status",
+                  "created_at"
+                ],
+                "type": "object"
+              },
+              {
+                "additionalProperties": false,
+                "properties": {
+                  "quota_used_bytes": {
+                    "description": "Live storage usage in bytes. Omitted when usage is temporarily unavailable.",
+                    "type": "integer"
+                  }
+                },
+                "type": "object"
+              }
+            ]
+          },
+          "meta": {
+            "additionalProperties": false,
+            "properties": {
+              "request_id": {
+                "example": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx",
+                "type": "string"
+              }
+            },
+            "required": [
+              "request_id"
+            ],
+            "type": "object"
+          }
+        },
+        "required": [
+          "data"
+        ],
+        "type": "object"
+      }
+    ],
+    "unevaluatedProperties": {
+      "not": {}
+    },
+    "x-fastmcp-top-level-schema": "MailboxMeItemResponse"
+  }
+}

addedOutput schema / required
```
Added value: +[
+  "result"
+]
```

First observedv1.0.0Jul 13, 2026

TDQS

A3.9/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered by structured data. The description adds the 'currently in use' mailbox targeting nuance, but it does not describe caching/304 behavior or edge cases; the schema's If-None-Match parameter description covers the 304 behavior instead.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with no filler; the main use-case is front-loaded in the first sentence and the return value in the second. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only profile tool with no required parameters, rich annotations, 100% schema parameter coverage, and an output schema, the description is sufficient. An agent has everything needed to invoke it and interpret the basic result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both params (mailbox_id and If-None-Match) are already documented in the schema. The description does not add parameter-level meaning beyond what the schema provides, which yields the baseline score of 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a clear verb ('identify', 'returns') and a specific resource ('authenticated mailbox' / 'mailbox key currently in use'), making the tool's function obvious. It does not explicitly distinguish itself from sibling tools like mailbox_get_identity or mailbox_get_session, so it stops short of full differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives a concrete usage context: 'before acting on mail', which tells an agent when this lightweight profile lookup is appropriate. It does not state when not to use it or name alternatives, so it lacks explicit exclusion/alternative guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.