Microsoft 365 MCP Server

send-mail

send-mail

Destructive

Send an email via Microsoft 365 with specified recipients, subject, body, and attachments. Supports JSON or MIME format.

Instructions

Send the message specified in the request body using either JSON or MIME format. When using JSON format, you can include a file attachment in the same sendMail action call. When using MIME format: This method saves the message in the Sent Items folder. Alternatively, create a draft message to send later. To learn more about the steps involved in the backend before a mail is delivered to recipients, see here.

💡 TIP: CRITICAL: Do not try to guess the email address of the recipients. Use the list-users tool to find the email address of the recipients.

Input Schema

TableJSON Schema

Name	Required	Description
`body`	Yes
`confirm`	No	For destructive operations when the confirm gate is enabled (MS365_MCP_REQUIRE_CONFIRM=true; off by default). Set to true only after the user has explicitly approved this action. When the gate is on, calls without confirm: true return { error: "confirmation_required" } without touching user data.
`includeHeaders`	No	Include response headers (including ETag) in the response metadata
`excludeResponse`	No	Exclude the full response body and only return success or failure indication

Schema Changelog

Changes observed during successful MCP inspections.

Changed29 schema fields changedv0.145.2Aug 22, 2026

removedInput schema / $defs

Removed value: -{
-  "def0": {
-    "additionalProperties": true,
-    "properties": {
-      "dateTime": {
-        "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
-        "type": "string"
-      },
-      "timeZone": {
-        "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
-        "type": [
-          "string",
-          "null"
-        ]
-      }
-    },
-    "type": "object"
-  },
-  "def1": {
-    "additionalProperties": true,
-    "properties": {
-      "emailAddress": {
-        "additionalProperties": true,
-        "properties": {
-          "address": {
-            "description": "The email address of the person or entity.",
-            "type": [
-              "string",
-              "null"
-            ]
-          },
-          "name": {
-            "description": "The display name of the person or entity.",
-            "type": [
-              "string",
-              "null"
-            ]
-          }
-        },
-        "type": "object"
-      }
-    },
-    "type": "object"
-  }
-}

removedInput schema / properties / body / properties / Message / properties / bccRecipients / items / $ref
```
Removed value: -"#/$defs/def1"
```
addedInput schema / properties / body / properties / Message / properties / bccRecipients / items / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / bccRecipients / items / properties

Added value: +{
+  "emailAddress": {
+    "additionalProperties": true,
+    "properties": {
+      "address": {
+        "description": "The email address of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "name": {
+        "description": "The display name of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  }
+}

addedInput schema / properties / body / properties / Message / properties / bccRecipients / items / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / ccRecipients / items / $ref
```
Removed value: -"#/$defs/def1"
```
addedInput schema / properties / body / properties / Message / properties / ccRecipients / items / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / ccRecipients / items / properties

Added value: +{
+  "emailAddress": {
+    "additionalProperties": true,
+    "properties": {
+      "address": {
+        "description": "The email address of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "name": {
+        "description": "The display name of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  }
+}

addedInput schema / properties / body / properties / Message / properties / ccRecipients / items / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / $ref
```
Removed value: -"#/$defs/def0"
```
addedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / additionalProperties
```
Added value: +true
```

added

Input schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / properties

Added value: +{
+  "dateTime": {
+    "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
+    "type": "string"
+  },
+  "timeZone": {
+    "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
+    "type": [
+      "string",
+      "null"
+    ]
+  }
+}

addedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / flag / properties / dueDateTime / $ref
```
Removed value: -"#/$defs/def0"
```
addedInput schema / properties / body / properties / Message / properties / flag / properties / dueDateTime / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / flag / properties / dueDateTime / properties

Added value: +{
+  "dateTime": {
+    "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
+    "type": "string"
+  },
+  "timeZone": {
+    "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
+    "type": [
+      "string",
+      "null"
+    ]
+  }
+}

addedInput schema / properties / body / properties / Message / properties / flag / properties / dueDateTime / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / flag / properties / startDateTime / $ref
```
Removed value: -"#/$defs/def0"
```
addedInput schema / properties / body / properties / Message / properties / flag / properties / startDateTime / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / flag / properties / startDateTime / properties

Added value: +{
+  "dateTime": {
+    "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
+    "type": "string"
+  },
+  "timeZone": {
+    "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
+    "type": [
+      "string",
+      "null"
+    ]
+  }
+}

addedInput schema / properties / body / properties / Message / properties / flag / properties / startDateTime / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / from / $ref
```
Removed value: -"#/$defs/def1"
```
addedInput schema / properties / body / properties / Message / properties / from / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / from / properties

Added value: +{
+  "emailAddress": {
+    "additionalProperties": true,
+    "properties": {
+      "address": {
+        "description": "The email address of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "name": {
+        "description": "The display name of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  }
+}

addedInput schema / properties / body / properties / Message / properties / from / type
```
Added value: +"object"
```
removedInput schema / properties / body / properties / Message / properties / toRecipients / items / $ref
```
Removed value: -"#/$defs/def1"
```
addedInput schema / properties / body / properties / Message / properties / toRecipients / items / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / toRecipients / items / properties

Added value: +{
+  "emailAddress": {
+    "additionalProperties": true,
+    "properties": {
+      "address": {
+        "description": "The email address of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "name": {
+        "description": "The display name of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  }
+}

addedInput schema / properties / body / properties / Message / properties / toRecipients / items / type
```
Added value: +"object"
```

Changed14 schema fields changedv0.134.4Jul 28, 2026

addedInput schema / $defs

Added value: +{
+  "def0": {
+    "additionalProperties": true,
+    "properties": {
+      "dateTime": {
+        "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
+        "type": "string"
+      },
+      "timeZone": {
+        "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  },
+  "def1": {
+    "additionalProperties": true,
+    "properties": {
+      "emailAddress": {
+        "additionalProperties": true,
+        "properties": {
+          "address": {
+            "description": "The email address of the person or entity.",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "name": {
+            "description": "The display name of the person or entity.",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "type": "object"
+      }
+    },
+    "type": "object"
+  }
+}

changedInput schema / properties / body / properties / Message / properties / bccRecipients / items / $ref
```
Previous value: -"#/properties/body/properties/Message/properties/from"New value: +"#/$defs/def1"
```
changedInput schema / properties / body / properties / Message / properties / ccRecipients / items / $ref
```
Previous value: -"#/properties/body/properties/Message/properties/from"New value: +"#/$defs/def1"
```
addedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / $ref
```
Added value: +"#/$defs/def0"
```
removedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / additionalProperties
```
Removed value: -true
```

removed

Input schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / properties

Removed value: -{
-  "dateTime": {
-    "description": "A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).",
-    "type": "string"
-  },
-  "timeZone": {
-    "description": "Represents a time zone, for example, 'Pacific Standard Time'. See below for more possible values.",
-    "type": [
-      "string",
-      "null"
-    ]
-  }
-}

removedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / type
```
Removed value: -"object"
```

changedInput schema / properties / body / properties / Message / properties / flag / properties / dueDateTime / $ref

Previous value: -"#/properties/body/properties/Message/properties/flag/properties/completedDateTime"New value: +"#/$defs/def0"

changedInput schema / properties / body / properties / Message / properties / flag / properties / startDateTime / $ref

Previous value: -"#/properties/body/properties/Message/properties/flag/properties/completedDateTime"New value: +"#/$defs/def0"

addedInput schema / properties / body / properties / Message / properties / from / $ref
```
Added value: +"#/$defs/def1"
```
removedInput schema / properties / body / properties / Message / properties / from / additionalProperties
```
Removed value: -true
```

removedInput schema / properties / body / properties / Message / properties / from / properties

Removed value: -{
-  "emailAddress": {
-    "additionalProperties": true,
-    "properties": {
-      "address": {
-        "description": "The email address of the person or entity.",
-        "type": [
-          "string",
-          "null"
-        ]
-      },
-      "name": {
-        "description": "The display name of the person or entity.",
-        "type": [
-          "string",
-          "null"
-        ]
-      }
-    },
-    "type": "object"
-  }
-}

removedInput schema / properties / body / properties / Message / properties / from / type
```
Removed value: -"object"
```
changedInput schema / properties / body / properties / Message / properties / toRecipients / items / $ref
```
Previous value: -"#/properties/body/properties/Message/properties/from"New value: +"#/$defs/def1"
```

Changed1 schema field changedv0.131.2Jul 18, 2026
- changedInput schema / additionalProperties
```
Previous value: -falseNew value: +true
```

Changed1 schema field changedv0.131.1Jul 11, 2026

addedInput schema / properties / confirm

Added value: +{
+  "description": "For destructive operations when the confirm gate is enabled (MS365_MCP_REQUIRE_CONFIRM=true; off by default). Set to true only after the user has explicitly approved this action. When the gate is on, calls without confirm: true return { error: \"confirmation_required\" } without touching user data.",
+  "type": "boolean"
+}

Addedv0.114.0May 28, 2026
Removedv0.112.2May 22, 2026
Addedv0.110.0May 18, 2026
Removedv0.108.0May 15, 2026

Changed21 schema fields changedv0.96.0May 4, 2026

changedInput schema / properties / body / additionalProperties
```
Previous value: -falseNew value: +true
```
addedInput schema / properties / body / properties / Message / properties / bccRecipients / items / $ref
```
Added value: +"#/properties/body/properties/Message/properties/from"
```
removedInput schema / properties / body / properties / Message / properties / bccRecipients / items / additionalProperties
```
Removed value: -false
```

removedInput schema / properties / body / properties / Message / properties / bccRecipients / items / properties

Removed value: -{
-  "emailAddress": {
-    "additionalProperties": false,
-    "properties": {
-      "address": {
-        "description": "The email address of the person or entity.",
-        "type": [
-          "string",
-          "null"
-        ]
-      },
-      "name": {
-        "description": "The display name of the person or entity.",
-        "type": [
-          "string",
-          "null"
-        ]
-      }
-    },
-    "type": "object"
-  }
-}

removedInput schema / properties / body / properties / Message / properties / bccRecipients / items / type
```
Removed value: -"object"
```
changedInput schema / properties / body / properties / Message / properties / body / additionalProperties
```
Previous value: -falseNew value: +true
```

changedInput schema / properties / body / properties / Message / properties / ccRecipients / items / $ref

Previous value: -"#/properties/body/properties/Message/properties/bccRecipients/items"New value: +"#/properties/body/properties/Message/properties/from"

changedInput schema / properties / body / properties / Message / properties / flag / additionalProperties
```
Previous value: -falseNew value: +true
```
changedInput schema / properties / body / properties / Message / properties / flag / properties / completedDateTime / additionalProperties
```
Previous value: -falseNew value: +true
```
removedInput schema / properties / body / properties / Message / properties / from / $ref
```
Removed value: -"#/properties/body/properties/Message/properties/bccRecipients/items"
```
addedInput schema / properties / body / properties / Message / properties / from / additionalProperties
```
Added value: +true
```

addedInput schema / properties / body / properties / Message / properties / from / properties

Added value: +{
+  "emailAddress": {
+    "additionalProperties": true,
+    "properties": {
+      "address": {
+        "description": "The email address of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "name": {
+        "description": "The display name of the person or entity.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  }
+}

addedInput schema / properties / body / properties / Message / properties / from / type
```
Added value: +"object"
```

changedInput schema / properties / body / properties / Message / properties / internetMessageHeaders / description

Previous value: -"A collection of message headers defined by RFC5322. The set includes message headers indicating the network path taken by a message from the sender to the recipient. It can also contain custom message headers that hold app data for the message.  Returned only on applying a $select query option. Read-only."New value: +"A collection of message headers defined by RFC5322. The set includes message headers indicating the network path taken by a message from the sender to the recipient. It can also contain custom message headers that hold app data for the message.  Requires $select to retrieve. Read-only."

changedInput schema / properties / body / properties / Message / properties / internetMessageHeaders / items / additionalProperties
```
Previous value: -falseNew value: +true
```

removedInput schema / properties / body / properties / Message / properties / isRead

Removed value: -{
-  "description": "Indicates whether the message has been read.",
-  "type": [
-    "boolean",
-    "null"
-  ]
-}

removedInput schema / properties / body / properties / Message / properties / isReadReceiptRequested

Removed value: -{
-  "description": "Indicates whether a read receipt is requested for the message.",
-  "type": [
-    "boolean",
-    "null"
-  ]
-}

addedInput schema / properties / body / properties / Message / properties / multiValueExtendedProperties

Added value: +{
+  "description": "The collection of multi-value extended properties defined for the message. Nullable.",
+  "items": {
+    "additionalProperties": true,
+    "properties": {
+      "id": {
+        "description": "The unique identifier for an entity. Read-only.",
+        "type": "string"
+      },
+      "value": {
+        "description": "A collection of property values.",
+        "items": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "type": "array"
+      }
+    },
+    "type": "object"
+  },
+  "type": "array"
+}

removedInput schema / properties / body / properties / Message / properties / parentFolderId

Removed value: -{
-  "description": "The unique identifier for the message's parent mailFolder.",
-  "type": [
-    "string",
-    "null"
-  ]
-}

addedInput schema / properties / body / properties / Message / properties / singleValueExtendedProperties

Added value: +{
+  "description": "The collection of single-value extended properties defined for the message. Nullable.",
+  "items": {
+    "additionalProperties": true,
+    "properties": {
+      "id": {
+        "description": "The unique identifier for an entity. Read-only.",
+        "type": "string"
+      },
+      "value": {
+        "description": "A property value.",
+        "type": [
+          "string",
+          "null"
+        ]
+      }
+    },
+    "type": "object"
+  },
+  "type": "array"
+}

addedInput schema / properties / body / properties / Message / properties / toRecipients

Added value: +{
+  "description": "The To: recipients for the message.",
+  "items": {
+    "$ref": "#/properties/body/properties/Message/properties/from"
+  },
+  "type": "array"
+}

First observedv0.31.0Jan 27, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the safety profile is known. The description adds valuable behavior: it explains that MIME format saves the message in Sent Items, and that JSON format supports file attachments in the same call. These specifics go beyond the annotations and help the agent anticipate consequences.

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

Conciseness3/5

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

The description is reasonably concise but contains a non-actionable link ('see here') and an irrelevant backend-information sentence. The critical tip is highlighted and front-loaded, which is good. However, the link is a dead end and the backend note adds little for an agent. Overall it is acceptable but not tightly focused.

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

Completeness4/5

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

For a tool with a very large, nested schema, the description covers the essential context: format options, attachment handling, default SaveToSentItems behavior, and the practical tip about recipient addresses. It does not describe response format, but there is no output schema, and the confirm parameter is self-documented in the schema. The description is sufficient for safe and effective invocation.

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

Parameters4/5

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

With 75% schema description coverage, the schema already documents many fields. The description adds meaning that the schema lacks by explaining the two request body formats (JSON vs MIME) and their implications (attachment support, Sent Items behavior). The tip about using list-users for recipient addresses also guides parameter construction, going beyond the schema's field descriptions.

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

Purpose5/5

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

The description clearly states the verb 'Send' and the resource 'the message specified in the request body.' It distinguishes this tool from sibling mail actions by explicitly mentioning JSON vs MIME formats and the alternative of creating a draft. The purpose is unambiguous and unique among the many mail-related siblings.

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?

The description provides clear context on when to use this tool: 'Send the message' and when to consider creating a draft ('Alternatively, create a draft message to send later'). It also gives a crucial operational guideline: 'Do not try to guess the email address of the recipients. Use the list-users tool.' This effectively routes the agent to a specific workflow, though it doesn't explicitly compare to send-draft-message.

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

Deploy Server

send-mail

Instructions

Input Schema

Schema Changelog

TDQS

Other Tools