diff --git a/.husky/pre-commit b/.husky/pre-commit
index 6697471..de886f7 100755
--- a/.husky/pre-commit
+++ b/.husky/pre-commit
@@ -1,5 +1,5 @@
 #!/bin/sh
 . "$(dirname "$0")/_/husky.sh"
 
-ts-node ./check-version.ts
-pretty-quick --staged
+npx ts-node ./check-version.ts
+npx pretty-quick --staged
diff --git a/lib/api.ts b/lib/api.ts
index dd7408e..edd41b5 100644
--- a/lib/api.ts
+++ b/lib/api.ts
@@ -1,7 +1,7 @@
 import type { RequestOptions } from 'https';
 import Request, { BearerAuth, RequestData } from './request';
 import { Region, RegionUS } from './regions';
-import { SendEmailRequest, SendPushRequest, SendSMSRequest } from './api/requests';
+import { SendEmailRequest, SendPushRequest, SendSMSRequest, SendInboxMessageRequest } from './api/requests';
 import { cleanEmail, isEmpty, isIdentifierType, MissingParamError } from './utils';
 import { Filter, IdentifierType } from './types';
 
@@ -93,6 +93,14 @@ export class APIClient {
     return this.request.post(`${this.apiRoot}/send/sms`, req.message);
   }
 
+  sendInboxMessage(req: SendInboxMessageRequest) {
+    if (!(req instanceof SendInboxMessageRequest)) {
+      throw new Error('"request" must be an instance of SendInboxMessageRequest');
+    }
+
+    return this.request.post(`${this.apiRoot}/send/inbox_message`, req.message);
+  }
+
   getCustomersByEmail(email: string) {
     if (typeof email !== 'string' || isEmpty(email)) {
       throw new Error('"email" must be a string');
@@ -168,4 +176,4 @@ export class APIClient {
   }
 }
 
-export { SendEmailRequest, SendPushRequest, SendSMSRequest } from './api/requests';
+export { SendEmailRequest, SendPushRequest, SendSMSRequest, SendInboxMessageRequest } from './api/requests';
diff --git a/lib/api/requests.ts b/lib/api/requests.ts
index 104390d..fc04ee6 100644
--- a/lib/api/requests.ts
+++ b/lib/api/requests.ts
@@ -204,3 +204,37 @@ export class SendSMSRequest {
     };
   }
 }
+
+export type InboxMessage = Partial<SendInboxMessageRequestOptions>;
+
+export type SendInboxMessageRequestRequiredOptions = {
+  identifiers: Identifiers;
+  transactional_message_id: string | number;
+};
+
+export type SendInboxMessageRequestOptionalOptions = Partial<{
+  disable_message_retention: boolean;
+  queue_draft: boolean;
+  message_data: Record<string, any>;
+  send_at: number;
+  language: string;
+}>;
+
+export type SendInboxMessageRequestOptions = SendInboxMessageRequestRequiredOptions &
+  SendInboxMessageRequestOptionalOptions & {};
+
+export class SendInboxMessageRequest {
+  message: InboxMessage;
+
+  constructor(opts: SendInboxMessageRequestOptions) {
+    this.message = {
+      identifiers: opts.identifiers,
+      transactional_message_id: opts.transactional_message_id,
+      disable_message_retention: opts.disable_message_retention,
+      queue_draft: opts.queue_draft,
+      message_data: opts.message_data,
+      send_at: opts.send_at,
+      language: opts.language,
+    };
+  }
+}
diff --git a/test/api.ts b/test/api.ts
index 63bfde3..fc9a37a 100644
--- a/test/api.ts
+++ b/test/api.ts
@@ -7,6 +7,7 @@ import {
   SendEmailRequest,
   SendPushRequest,
   SendSMSRequest,
+  SendInboxMessageRequest,
 } from '../lib/api';
 import { RegionUS, RegionEU } from '../lib/regions';
 import { Filter, IdentifierType } from '../lib/types';
@@ -565,3 +566,83 @@ test('#sendSMS: error', async (t) => {
 
   t.truthy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/sms`, req.message));
 });
+
+test('sendInboxMessage: passing in a plain object throws an error', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+
+  let req = { identifiers: { id: '2' }, transactional_message_id: 1 };
+
+  t.throws(() => t.context.client.sendInboxMessage(req as any), {
+    message: /"request" must be an instance of SendInboxMessageRequest/,
+  });
+  t.falsy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/inbox_message`));
+});
+
+test('#sendInboxMessage: with template: success', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+  let req = new SendInboxMessageRequest({
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+  });
+  t.context.client.sendInboxMessage(req);
+  t.truthy(
+    (t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/inbox_message`, req.message),
+  );
+  t.is(req.message.transactional_message_id, 1);
+  t.deepEqual(req.message.identifiers, { id: '2' });
+});
+
+test('#sendInboxMessage: with optional parameters: success', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+  let req = new SendInboxMessageRequest({
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+    message_data: { key: 'value' },
+    disable_message_retention: true,
+    queue_draft: true,
+    send_at: 1234567890,
+    language: 'en',
+  });
+  t.context.client.sendInboxMessage(req);
+  t.truthy(
+    (t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/inbox_message`, req.message),
+  );
+  t.is(req.message.transactional_message_id, 1);
+  t.deepEqual(req.message.identifiers, { id: '2' });
+  t.deepEqual(req.message.message_data, { key: 'value' });
+  t.true(req.message.disable_message_retention);
+  t.true(req.message.queue_draft);
+  t.is(req.message.send_at, 1234567890);
+  t.is(req.message.language, 'en');
+});
+
+test('#sendInboxMessage: with email identifier: success', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+  let req = new SendInboxMessageRequest({
+    identifiers: { email: 'test@example.com' },
+    transactional_message_id: 1,
+  });
+  t.context.client.sendInboxMessage(req);
+  t.truthy(
+    (t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/inbox_message`, req.message),
+  );
+  t.is(req.message.transactional_message_id, 1);
+  t.deepEqual(req.message.identifiers, { email: 'test@example.com' });
+});
+
+test('#sendInboxMessage: error', async (t) => {
+  sinon.stub(t.context.client.request, 'post').rejects({ message: 'sample error', statusCode: 400 });
+
+  let req = new SendInboxMessageRequest({
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+  });
+  t.context.client.sendInboxMessage(req).catch((err) => {
+    t.is(err.message, 'sample error');
+    t.is(err.statusCode, 400);
+  });
+
+  t.truthy(
+    (t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/inbox_message`, req.message),
+  );
+});