feat: add messages resend

README.md

@@ -66,7 +66,7 @@ lettermint = Lettermint(
 )
 ```
 
-Each part uses its own token and never falls back to the other one. If the token a method needs is missing, it raises `LettermintConfigError` that names the argument (`domains.list needs team_token; …`), before any request. `lettermint.ping()` uses the team token when it is set, otherwise the sending token. `messages.reschedule()` and `messages.cancel()` accept either token in the same way.
+Each part uses its own token and never falls back to the other one. If the token a method needs is missing, it raises `LettermintConfigError` that names the argument (`domains.list needs team_token; …`), before any request. `lettermint.ping()` uses the team token when it is set, otherwise the sending token. `messages.reschedule()`, `messages.cancel()` and `messages.resend()` accept either token in the same way.
 
 You can also pass a single token string. The SDK chooses its type by the format: `lm_team_` followed by letters and digits is a team token, and `lm_` followed by letters and digits is a sending token. Any other value, such as an SSO verification token (`lm_sso_…`), raises `LettermintConfigError`; pass `sending_token=` or `team_token=` explicitly in that case.
 
@@ -257,10 +257,17 @@ stats = lettermint.stats.retrieve({"from": "2026-10-01", "to": "2026-10-31"})
 html = lettermint.messages.html("message-id")
 ```
 
+`messages.resend()` sends the stored content of a sent message again, as a new message with its own ID. Leave out the body to resend to every original recipient, or choose some of them. It takes an idempotency key like `emails.send()`. A message can be resent while its content is retained (the API answers `410` otherwise), at most 5 times in 24 hours.
+
+```python
+resent = lettermint.messages.resend("message-id", {"recipients": ["jane@example.com"]})
+print(resent["message_id"])  # the new message; it links back through resent_from_message_id
+```
+
 | Attribute | Methods |
 | --- | --- |
 | `domains` | `list`, `iterate`, `create`, `retrieve`, `delete`, `verify_dns_records`, `verify_dns_record`, `update_projects` |
-| `messages` | `list`, `iterate`, `retrieve`, `events`, `iterate_events`, `source`, `html`, `text`, `reschedule`, `cancel`, `process` |
+| `messages` | `list`, `iterate`, `retrieve`, `events`, `iterate_events`, `source`, `html`, `text`, `reschedule`, `cancel`, `process`, `resend` |
 | `projects` | `list`, `iterate`, `create`, `retrieve`, `update`, `delete`, `rotate_token` |
 | `projects.report_forwarding` | `retrieve`, `update`, `delete`, `verify`, `resend_code` |
 | `routes` | `list(project_id)`, `iterate(project_id)`, `create(project_id, …)`, `retrieve`, `update`, `delete`, `verify_inbound_domain` |

src/lettermint/_async/resources.py

@@ -1,8 +1,8 @@
 """The Team API sub-clients of :class:`~lettermint.AsyncLettermint`.
 
-Every method uses the team token, except ``messages.reschedule`` and
-``messages.cancel``, which use the team token when it is set and otherwise
-the sending token.
+Every method uses the team token, except ``messages.reschedule``,
+``messages.cancel`` and ``messages.resend``, which use the team token when it
+is set and otherwise the sending token.
 """
 
 from __future__ import annotations
@@ -47,13 +47,15 @@
     MessageEventData,
     MessageListData,
     MessageResponse,
+    PendingSendMailResponse,
     ProcessInboundMessageResponse,
     ProjectCreatedData,
     ProjectData,
     ProjectListData,
     ProjectMutationResponse,
     ReportForwardingRequest,
     RescheduleMessageRequest,
+    ResendMessageRequest,
     ResendReportForwardingCodeResponse,
     RotateProjectTokenResponse,
     RouteData,
@@ -265,8 +267,8 @@ async def update_projects(
 class AsyncMessages(AsyncResource):
     """Sent and received messages. Team token.
 
-    ``reschedule`` and ``cancel`` also accept the sending token when no team
-    token is configured.
+    ``reschedule``, ``cancel`` and ``resend`` also accept the sending token when
+    no team token is configured.
     """
 
     async def list(
@@ -412,6 +414,34 @@ async def process(
             ),
         )
 
+    async def resend(
+        self,
+        message_id: str,
+        body: ResendMessageRequest | None = None,
+        *,
+        idempotency_key: str | None = None,
+        timeout: float | None = None,
+    ) -> PendingSendMailResponse:
+        """Sends the stored content of a sent message again, as a new message with its own ID.
+
+        Without ``body``, every original recipient receives it again; pass
+        ``{"recipients": [...]}`` to choose some of them. The new message links to
+        the original through ``resent_from_message_id``. A message can be resent
+        while its content is retained (otherwise HTTP 410), at most 5 times in 24
+        hours.
+        """
+        return cast(
+            PendingSendMailResponse,
+            await self._request(
+                "POST /messages/{messageId}/resend",
+                "messages.resend",
+                path={"messageId": message_id},
+                **({} if body is None else {"body": body}),
+                idempotency_key=idempotency_key,
+                timeout=timeout,
+            ),
+        )
+
 
 class AsyncReportForwarding(AsyncResource):
     """DMARC and complaint report forwarding of a project. Team token."""

src/lettermint/_generated/__init__.py

@@ -1,6 +1,6 @@
 # Generated by lettermint/sdk-generator — do not edit.
-# Spec: lettermint/lettermint@bff20c7d86dd05b926713f89c0ad716ef630ae21 (main)
-# sending-openapi.json SHA-256: 958303afdf2971b372cab97e72845db2568bc0b6cb6f5c41b2a0dad0386df15d
-# team-openapi.json SHA-256: 04718e1e006be90fe586f30754a73a4fd69233119dc36862ded9fb98d69aa138
+# Spec: lettermint/lettermint@0f2c60ed7779f89b3960277da896ceffe893eae6 (main)
+# sending-openapi.json SHA-256: 8d5e962e57d79ab08be52147c094657b681768f06940a76c8eec1b1e03df54cc
+# team-openapi.json SHA-256: e1a0a212f79caf218caa03e9b7f23842b66deba93e2794a49ac02def30803593
 # Naming profile: next
 """Generated from the Lettermint OpenAPI specifications. Do not edit; regenerate."""

src/lettermint/_generated/operations.py

@@ -1,7 +1,7 @@
 # Generated by lettermint/sdk-generator — do not edit.
-# Spec: lettermint/lettermint@bff20c7d86dd05b926713f89c0ad716ef630ae21 (main)
-# sending-openapi.json SHA-256: 958303afdf2971b372cab97e72845db2568bc0b6cb6f5c41b2a0dad0386df15d
-# team-openapi.json SHA-256: 04718e1e006be90fe586f30754a73a4fd69233119dc36862ded9fb98d69aa138
+# Spec: lettermint/lettermint@0f2c60ed7779f89b3960277da896ceffe893eae6 (main)
+# sending-openapi.json SHA-256: 8d5e962e57d79ab08be52147c094657b681768f06940a76c8eec1b1e03df54cc
+# team-openapi.json SHA-256: e1a0a212f79caf218caa03e9b7f23842b66deba93e2794a49ac02def30803593
 # Naming profile: next
 """Every operation of the Sending and Team APIs, keyed by ``"<METHOD> <path>"``.
 
@@ -689,6 +689,22 @@ class Operation:
             pagination=None,
             deprecated=False,
         ),
+        # Resend a message
+        "POST /messages/{messageId}/resend": Operation(
+            operation_id="resendMessage",
+            method="POST",
+            path="/messages/{messageId}/resend",
+            auth="either",
+            surfaces=("team",),
+            path_params=("messageId",),
+            query=None,
+            headers=("Idempotency-Key",),
+            request=RequestBody(type="ResendMessageRequest", content_type="application/json", required=False),
+            response=ResponseBody(status=(202,), content_type="application/json", type="PendingSendMailResponse"),
+            errors={401: ("ErrorMessage", "ApiErrorBody"), 403: ("ApiErrorBody", "ErrorMessage"), 404: ("ErrorMessage", "ApiErrorBody"), 409: ("ApiErrorBody", "ErrorMessage"), 410: ("ApiErrorBody",), 422: ("ApiErrorBody", "ValidationErrorBody", "ErrorMessage"), 429: ("ApiErrorBody",), 500: ("ApiErrorBody",)},
+            pagination=None,
+            deprecated=False,
+        ),
         # Create a new project
         "POST /projects": Operation(
             operation_id="createProject",
@@ -814,7 +830,7 @@ class Operation:
             headers=("Idempotency-Key",),
             request=RequestBody(type="SendBatchMailRequest", content_type="application/json", required=True),
             response=ResponseBody(status=(202,), content_type="application/json", type="SendBatchMailResponse"),
-            errors={401: ("ErrorMessage",), 403: ("ApiErrorBody",), 409: ("ErrorMessage",), 422: ("ApiErrorBody", "ValidationErrorBody", "ErrorMessage"), 429: ("ApiErrorBody",), 500: ("ApiErrorBody",)},
+            errors={401: ("ErrorMessage",), 403: ("ApiErrorBody",), 409: ("ApiErrorBody", "ErrorMessage"), 422: ("ApiErrorBody", "ValidationErrorBody", "ErrorMessage"), 429: ("ApiErrorBody",), 500: ("ApiErrorBody",)},
             pagination=None,
             deprecated=False,
         ),

src/lettermint/_generated/types.py

@@ -1,7 +1,7 @@
 # Generated by lettermint/sdk-generator — do not edit.
-# Spec: lettermint/lettermint@bff20c7d86dd05b926713f89c0ad716ef630ae21 (main)
-# sending-openapi.json SHA-256: 958303afdf2971b372cab97e72845db2568bc0b6cb6f5c41b2a0dad0386df15d
-# team-openapi.json SHA-256: 04718e1e006be90fe586f30754a73a4fd69233119dc36862ded9fb98d69aa138
+# Spec: lettermint/lettermint@0f2c60ed7779f89b3960277da896ceffe893eae6 (main)
+# sending-openapi.json SHA-256: 8d5e962e57d79ab08be52147c094657b681768f06940a76c8eec1b1e03df54cc
+# team-openapi.json SHA-256: e1a0a212f79caf218caa03e9b7f23842b66deba93e2794a49ac02def30803593
 # Naming profile: next
 """Request and response types of the Lettermint API.
 
@@ -162,6 +162,7 @@
     "ReportForwardingRequest",
     "ReportForwardingResource",
     "RescheduleMessageRequest",
+    "ResendMessageRequest",
     "ResendReportForwardingCodeResponse",
     "RotateProjectTokenResponse",
     "RouteData",
@@ -173,6 +174,7 @@
     "SandboxResult",
     "ScheduledMessage",
     "ScheduledSendMailResponse",
+    "SendBatchMailItem",
     "SendBatchMailRequest",
     "SendBatchMailResponse",
     "SendMailRequest",
@@ -1797,6 +1799,8 @@ class CursorPage(TypedDict, Generic[T]):
         "spam_symbols": NotRequired["list[SpamSymbol]"],
         "route_id": Required[str],
         "created_at": Required[str],
+        # The ID of the message this message resent. Null when it is not a resend
+        "resent_from_message_id": NotRequired[str | None],
     },
 )
 
@@ -2133,6 +2137,15 @@ class CursorPage(TypedDict, Generic[T]):
 )
 
 
+ResendMessageRequest = TypedDict(
+    "ResendMessageRequest",
+    {
+        # Recipients of the original message to resend to. Omit to resend to every original recipient.
+        "recipients": NotRequired[list[str]],
+    },
+)
+
+
 ResendReportForwardingCodeResponse = TypedDict(
     "ResendReportForwardingCodeResponse",
     {
@@ -2282,8 +2295,8 @@ class CursorPage(TypedDict, Generic[T]):
 )
 
 
-SendMailRequest = TypedDict(
-    "SendMailRequest",
+SendBatchMailItem = TypedDict(
+    "SendBatchMailItem",
     {
         "route": NotRequired[str],
         "from": Required[str],
@@ -2314,11 +2327,13 @@ class CursorPage(TypedDict, Generic[T]):
         "html": NotRequired[str | None],
         "text": NotRequired[str | None],
         "attachments": NotRequired["list[MessageAttachmentInput]"],
+        # Optional key (1-255 characters) that makes this email safe to send again, in this or a later batch. If an email with the same key and content was accepted in the last 24 hours, its original result is returned and it is not sent again. Keys must be unique within a batch. Reusing a key with different content, or while the email with that key is still being processed, rejects the whole batch with `409 Conflict` and sends nothing.
+        "idempotency_key": NotRequired[str],
     },
 )
 
 
-SendBatchMailRequest: TypeAlias = list[SendMailRequest]
+SendBatchMailRequest: TypeAlias = list[SendBatchMailItem]
 
 
 SendMailResponse: TypeAlias = PendingSendMailResponse | ScheduledSendMailResponse
@@ -2327,6 +2342,42 @@ class CursorPage(TypedDict, Generic[T]):
 SendBatchMailResponse: TypeAlias = list[SendMailResponse]
 
 
+SendMailRequest = TypedDict(
+    "SendMailRequest",
+    {
+        "route": NotRequired[str],
+        "from": Required[str],
+        "to": Required[list[str]],
+        "cc": NotRequired[list[str]],
+        "bcc": NotRequired[list[str]],
+        "reply_to": NotRequired[list[str]],
+        "subject": Required[str],
+        # ISO 8601 or English delivery time. A time without a timezone uses UTC.
+        "scheduled_at": NotRequired[str],
+        # The result that a Sandbox project simulates for every recipient.
+        "sandbox_result": NotRequired["SandboxResult"],
+        # Custom headers to include in the email. To preserve a submitted RFC Message-ID,
+        # include both Message-ID and X-LM-Preserve-Message-ID with a string value of true or 1.
+        # Header names and control values are case-insensitive; false or 0 retains replacement.
+        # Send values as plain text: Lettermint encodes non-ASCII characters and repairs small formatting
+        # errors, such as line breaks, control characters and missing angle brackets. Header names must
+        # be printable ASCII without a colon.
+        "headers": NotRequired[dict[str, str]],
+        # Metadata to track with the email (not added as email headers).
+        "metadata": NotRequired[dict[str, str]],
+        # Tag to categorize and filter emails (alphanumeric, underscores, hyphens, spaces allowed).
+        "tag": NotRequired[str | None],
+        # Reusable exact-match tags. Names must be unique and are case-sensitive.
+        "tags": NotRequired["list[MessageTagInput]"],
+        # Per-email settings that override the selected route settings for this email only.
+        "settings": NotRequired["SendMailRequestSettings"],
+        "html": NotRequired[str | None],
+        "text": NotRequired[str | None],
+        "attachments": NotRequired["list[MessageAttachmentInput]"],
+    },
+)
+
+
 # Per-email settings that override the selected route settings for this email only.
 SendMailRequestSettings = TypedDict(
     "SendMailRequestSettings",

src/lettermint/_sync/resources.py

@@ -1,9 +1,9 @@
 # Generated from src/lettermint/_async/resources.py by scripts/unasync.py — do not edit.
 """The Team API sub-clients of :class:`~lettermint.Lettermint`.
 
-Every method uses the team token, except ``messages.reschedule`` and
-``messages.cancel``, which use the team token when it is set and otherwise
-the sending token.
+Every method uses the team token, except ``messages.reschedule``,
+``messages.cancel`` and ``messages.resend``, which use the team token when it
+is set and otherwise the sending token.
 """
 
 from __future__ import annotations
@@ -48,13 +48,15 @@
     MessageEventData,
     MessageListData,
     MessageResponse,
+    PendingSendMailResponse,
     ProcessInboundMessageResponse,
     ProjectCreatedData,
     ProjectData,
     ProjectListData,
     ProjectMutationResponse,
     ReportForwardingRequest,
     RescheduleMessageRequest,
+    ResendMessageRequest,
     ResendReportForwardingCodeResponse,
     RotateProjectTokenResponse,
     RouteData,
@@ -266,8 +268,8 @@ def update_projects(
 class Messages(Resource):
     """Sent and received messages. Team token.
 
-    ``reschedule`` and ``cancel`` also accept the sending token when no team
-    token is configured.
+    ``reschedule``, ``cancel`` and ``resend`` also accept the sending token when
+    no team token is configured.
     """
 
     def list(
@@ -413,6 +415,34 @@ def process(
             ),
         )
 
+    def resend(
+        self,
+        message_id: str,
+        body: ResendMessageRequest | None = None,
+        *,
+        idempotency_key: str | None = None,
+        timeout: float | None = None,
+    ) -> PendingSendMailResponse:
+        """Sends the stored content of a sent message again, as a new message with its own ID.
+
+        Without ``body``, every original recipient receives it again; pass
+        ``{"recipients": [...]}`` to choose some of them. The new message links to
+        the original through ``resent_from_message_id``. A message can be resent
+        while its content is retained (otherwise HTTP 410), at most 5 times in 24
+        hours.
+        """
+        return cast(
+            PendingSendMailResponse,
+            self._request(
+                "POST /messages/{messageId}/resend",
+                "messages.resend",
+                path={"messageId": message_id},
+                **({} if body is None else {"body": body}),
+                idempotency_key=idempotency_key,
+                timeout=timeout,
+            ),
+        )
+
 
 class ReportForwarding(Resource):
     """DMARC and complaint report forwarding of a project. Team token."""