feat(api): support scheduled message delivery

src/main/java/co/lettermint/api/ApiClient.java

@@ -7,7 +7,7 @@
 import java.net.URLEncoder;
 import java.util.Map;
 
 public class ApiClient {
     private final LettermintClient client;
     private final DomainsEndpoint domains;
     private final MessagesEndpoint messages;
@@ -18,7 +18,7 @@
     private final TeamEndpoint team;
     private final WebhooksEndpoint webhooks;
 
     public ApiClient(String apiToken, String baseUrl) {
         this.client = new LettermintClient(apiToken, baseUrl, LettermintClient.AuthMode.BEARER);
         this.domains = new DomainsEndpoint(client);
         this.messages = new MessagesEndpoint(client);
@@ -78,7 +78,7 @@
         }
     }
 
     public static class DomainsEndpoint {
         private final LettermintClient client;
 
         DomainsEndpoint(LettermintClient client) {
@@ -118,7 +118,7 @@
         }
     }
 
     public static class MessagesEndpoint {
         private final LettermintClient client;
 
         MessagesEndpoint(LettermintClient client) {
@@ -137,6 +137,14 @@
             return client.get("/messages/" + segment(messageId), MessageData.class);
         }
 
+        public RescheduleMessageResponse reschedule(String messageId, RescheduleMessageRequest payload) {
+            return client.patch("/messages/" + segment(messageId), payload, RescheduleMessageResponse.class);
+        }
+
+        public RescheduleMessageResponse cancel(String messageId) {
+            return client.post("/messages/" + segment(messageId) + "/cancel", null, RescheduleMessageResponse.class);
+        }
+
         public MessageEventsResponse events(String messageId) {
             return events(messageId, null);
         }
@@ -158,7 +166,7 @@
         }
     }
 
     public static class ProjectsEndpoint {
         private final LettermintClient client;
 
         ProjectsEndpoint(LettermintClient client) {
@@ -206,7 +214,7 @@
         }
     }
 
     public static class RoutesEndpoint {
         private final LettermintClient client;
 
         RoutesEndpoint(LettermintClient client) {
@@ -230,7 +238,7 @@
         }
     }
 
     public static class StatsEndpoint {
         private final LettermintClient client;
 
         StatsEndpoint(LettermintClient client) {
@@ -246,7 +254,7 @@
         }
     }
 
     public static class SuppressionsEndpoint {
         private final LettermintClient client;
 
         SuppressionsEndpoint(LettermintClient client) {
@@ -270,7 +278,7 @@
         }
     }
 
     public static class TeamEndpoint {
         private final LettermintClient client;
 
         TeamEndpoint(LettermintClient client) {
@@ -314,7 +322,7 @@
         }
     }
 
     public static class WebhooksEndpoint {
         private final LettermintClient client;
 
         WebhooksEndpoint(LettermintClient client) {

src/main/java/co/lettermint/client/LettermintClient.java

@@ -111,6 +111,10 @@ public <T> T put(String path, Object payload, Class<T> responseClass) {
         return request("PUT", url(path, null), payload, responseClass, null, null);
     }
 
+    public <T> T patch(String path, Object payload, Class<T> responseClass) {
+        return request("PATCH", url(path, null), payload, responseClass, null, null);
+    }
+
     public <T> T delete(String path, Class<T> responseClass) {
         return request("DELETE", url(path, null), null, responseClass, null, null);
     }
@@ -148,6 +152,8 @@ private <T> T request(String method, String requestUrl, Object payload, Class<T>
             requestBuilder.post(body != null ? body : RequestBody.create(new byte[0], JSON));
         } else if ("PUT".equals(method)) {
             requestBuilder.put(body != null ? body : RequestBody.create(new byte[0], JSON));
+        } else if ("PATCH".equals(method)) {
+            requestBuilder.patch(body != null ? body : RequestBody.create(new byte[0], JSON));
         } else if ("DELETE".equals(method)) {
             requestBuilder.delete();
         } else {

src/main/java/co/lettermint/endpoints/EmailEndpoint.java

@@ -20,6 +20,7 @@
     private List<String> bcc;
     private List<String> replyTo;
     private String subject;
+    private String scheduledAt;
     private String html;
     private String text;
     private Map<String, String> headers;
@@ -46,6 +47,7 @@
         this.bcc = new ArrayList<>();
         this.replyTo = new ArrayList<>();
         this.subject = null;
+        this.scheduledAt = null;
         this.html = null;
         this.text = null;
         this.headers = new LinkedHashMap<>();
@@ -62,7 +64,7 @@
      * Set the sender email address.
      * Format: {@code "Name <email>"} or just {@code "email"}
      */
     public EmailEndpoint from(String from) {
         this.from = from;
         return this;
     }
@@ -70,7 +72,7 @@
     /**
      * Set recipient email addresses. Replaces any existing recipients.
      */
     public EmailEndpoint to(String... emails) {
         this.to = new ArrayList<>(Arrays.asList(emails));
         return this;
     }
@@ -78,7 +80,7 @@
     /**
      * Set CC email addresses. Replaces any existing CC recipients.
      */
     public EmailEndpoint cc(String... emails) {
         this.cc = new ArrayList<>(Arrays.asList(emails));
         return this;
     }
@@ -86,7 +88,7 @@
     /**
      * Set BCC email addresses. Replaces any existing BCC recipients.
      */
     public EmailEndpoint bcc(String... emails) {
         this.bcc = new ArrayList<>(Arrays.asList(emails));
         return this;
     }
@@ -94,7 +96,7 @@
     /**
      * Set reply-to email addresses. Replaces any existing reply-to addresses.
      */
     public EmailEndpoint replyTo(String... emails) {
         this.replyTo = new ArrayList<>(Arrays.asList(emails));
         return this;
     }
@@ -107,6 +109,12 @@
         return this;
     }
 
+    /** Set the requested delivery time for the email. */
+    public EmailEndpoint scheduledAt(String scheduledAt) {
+        this.scheduledAt = scheduledAt;
+        return this;
+    }
+
     /**
      * Set the HTML content of the email.
      */
@@ -296,6 +304,10 @@
             payload.put("subject", subject);
         }
 
+        if (scheduledAt != null) {
+            payload.put("scheduled_at", scheduledAt);
+        }
+
         if (html != null) {
             payload.put("html", html);
         }

src/main/java/co/lettermint/models/api/MessageData.java

@@ -19,6 +19,9 @@ public class MessageData {
     @JsonProperty("status_changed_at")
     public String statusChangedAt;
 
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
+
     @JsonProperty("tag")
     public String tag;
 

src/main/java/co/lettermint/models/api/MessageEventType.java

@@ -1,6 +1,10 @@
 package co.lettermint.models.api;
 
 public final class MessageEventType {
+    public static final String SCHEDULED = "scheduled";
+    public static final String RESCHEDULED = "rescheduled";
+    public static final String CANCELED = "canceled";
+    public static final String RELEASED = "released";
     public static final String QUEUED = "queued";
     public static final String PROCESSED = "processed";
     public static final String SUPPRESSED = "suppressed";

src/main/java/co/lettermint/models/api/MessageListData.java

@@ -16,6 +16,9 @@ public class MessageListData {
     @JsonProperty("status")
     public String status;
 
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
+
     @JsonProperty("spam_score")
     public Double spamScore;
 

src/main/java/co/lettermint/models/api/MessageStatus.java

@@ -1,6 +1,7 @@
 package co.lettermint.models.api;
 
 public final class MessageStatus {
+    public static final String SCHEDULED = "scheduled";
     public static final String PENDING = "pending";
     public static final String QUEUED = "queued";
     public static final String SUPPRESSED = "suppressed";
@@ -15,6 +16,7 @@ public final class MessageStatus {
     public static final String BLOCKED = "blocked";
     public static final String POLICYREJECTED = "policy_rejected";
     public static final String UNSUBSCRIBED = "unsubscribed";
+    public static final String CANCELED = "canceled";
 
     private MessageStatus() {}
 }

src/main/java/co/lettermint/models/api/RescheduleMessageRequest.java

@@ -0,0 +1,10 @@
+package co.lettermint.models.api;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class RescheduleMessageRequest {
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
+}

src/main/java/co/lettermint/models/api/RescheduleMessageResponse.java

@@ -0,0 +1,16 @@
+package co.lettermint.models.api;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class RescheduleMessageResponse {
+    @JsonProperty("message_id")
+    public String messageId;
+
+    @JsonProperty("status")
+    public String status;
+
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
+}

src/main/java/co/lettermint/models/api/SendMailRequest.java

@@ -28,6 +28,9 @@ public class SendMailRequest {
     @JsonProperty("subject")
     public String subject;
 
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
+
     @JsonProperty("headers")
     public Map<String, String> headers;
 

src/main/java/co/lettermint/models/api/SendMailResponse.java

@@ -10,4 +10,7 @@ public class SendMailResponse {
 
     @JsonProperty("status")
     public String status;
+
+    @JsonProperty("scheduled_at")
+    public String scheduledAt;
 }

src/test/java/co/lettermint/ApiClientTest.java

@@ -145,6 +145,29 @@ void rawMessageEndpointsPreserveResponseBody() throws Exception {
         }
     }
 
+    @Test
+    void schedulesMessageChangesWithTypedResponses() throws Exception {
+        try (MockWebServer server = new MockWebServer()) {
+            server.enqueue(new MockResponse().setHeader("Content-Type", "application/json").setBody("{\"message_id\":\"msg/id\",\"status\":\"scheduled\",\"scheduled_at\":\"2026-08-27T09:00:00Z\"}"));
+            server.enqueue(new MockResponse().setHeader("Content-Type", "application/json").setBody("{\"message_id\":\"msg/id\",\"status\":\"canceled\",\"scheduled_at\":null}"));
+            server.start();
+
+            ApiClient api = Lettermint.api("api-token", server.url("/v1").toString());
+            co.lettermint.models.api.RescheduleMessageRequest payload = new co.lettermint.models.api.RescheduleMessageRequest();
+            payload.scheduledAt = "2026-08-27T09:00:00Z";
+            assertEquals("scheduled", api.messages().reschedule("msg/id", payload).status);
+            assertEquals("canceled", api.messages().cancel("msg/id").status);
+
+            RecordedRequest reschedule = server.takeRequest();
+            assertEquals("PATCH", reschedule.getMethod());
+            assertEquals("/v1/messages/msg%2Fid", reschedule.getPath());
+            assertTrue(reschedule.getBody().readUtf8().contains("scheduled_at"));
+            RecordedRequest cancel = server.takeRequest();
+            assertEquals("POST", cancel.getMethod());
+            assertEquals("/v1/messages/msg%2Fid/cancel", cancel.getPath());
+        }
+    }
+
     @Test
     void publicClientRejectsAbsoluteRequestPaths() throws Exception {
         Lettermint lettermint = new Lettermint("sending-token", "https://api.example.test/v1");
@@ -159,7 +182,7 @@ void publicClientRejectsAbsoluteRequestPaths() throws Exception {
 
     @Test
     void generatedApiModelsMatchCurrentTeamSchema() {
-        assertEquals("auto_replied", co.lettermint.models.api.MessageEventType.AUTOREPLIED);
+        assertEquals("scheduled", co.lettermint.models.api.MessageEventType.SCHEDULED);
         assertEquals("message.auto_replied", co.lettermint.models.api.WebhookEvent.MESSAGEAUTOREPLIED);
         assertEquals("admin", co.lettermint.models.api.BuiltInTeamRole.ADMIN);
         assertEquals("enforced", co.lettermint.models.api.TlsPolicy.ENFORCED);
@@ -210,6 +233,7 @@ void generatedApiModelsMatchCurrentTeamSchema() {
 
         co.lettermint.models.api.MessageListData message = new co.lettermint.models.api.MessageListData();
         message.spamScore = 2.5;
+        message.scheduledAt = "2026-08-27T09:00:00Z";
 
         assertFalse(routeUpdate.settings.generatePlaintextFallback);
         assertEquals("enforced", routeUpdate.settings.tls);
@@ -226,6 +250,7 @@ void generatedApiModelsMatchCurrentTeamSchema() {
         assertEquals("managed_cname", domain.dkimMode);
         assertEquals("msg_123", recipient.sourceMessage.id);
         assertEquals(2.5, message.spamScore);
+        assertEquals("2026-08-27T09:00:00Z", message.scheduledAt);
     }
 
     @Test
@@ -243,6 +268,8 @@ void apiExposesDocumentedOperations() throws Exception {
         methods.put("v1.blockedFileTypes", api.getClass().getMethod("blockedFileTypes"));
         methods.put("message.index", api.messages().getClass().getMethod("list"));
         methods.put("message.show", api.messages().getClass().getMethod("retrieve", String.class));
+        methods.put("rescheduleMessage", api.messages().getClass().getMethod("reschedule", String.class, co.lettermint.models.api.RescheduleMessageRequest.class));
+        methods.put("cancelScheduledMessage", api.messages().getClass().getMethod("cancel", String.class));
         methods.put("message.events", api.messages().getClass().getMethod("events", String.class));
         methods.put("message.source", api.messages().getClass().getMethod("source", String.class));
         methods.put("message.html", api.messages().getClass().getMethod("html", String.class));