diff --git a/common/locales/en/api-v3.json b/common/locales/en/api-v3.json
index e9dcd2d86d..2a1cf8319c 100644
--- a/common/locales/en/api-v3.json
+++ b/common/locales/en/api-v3.json
@@ -117,5 +117,9 @@
   "missingPetFoodFeed": "\"pet\" and \"food\" are required parameters.",
   "invalidPetName": "Invalid pet name supplied.",
   "missingEggHatchingPotionHatch": "\"egg\" and \"hatchingPotion\" are required parameters.",
-  "invalidTypeEquip": "\"type\" must be one of 'equipped', 'pet', 'mount', 'costume'."
+  "invalidTypeEquip": "\"type\" must be one of 'equipped', 'pet', 'mount', 'costume'.",
+  "cannoyBuyItem": "You can't buy this item",
+  "messageRequired": "A message is required.",
+  "toUserIDRequired": "A toUserId is required",
+  "notAuthorizedToSendMessageToThisUser": "Can't send message to this user."
 }
diff --git a/test/api/v3/integration/members/POST-send_private_message.test.js b/test/api/v3/integration/members/POST-send_private_message.test.js
new file mode 100644
index 0000000000..013f741708
--- /dev/null
+++ b/test/api/v3/integration/members/POST-send_private_message.test.js
@@ -0,0 +1,171 @@
+import {
+  generateUser,
+  translate as t,
+} from '../../../../helpers/api-v3-integration.helper';
+import { v4 as generateUUID } from 'uuid';
+
+describe('POST /send-private-message', () => {
+  let userToSendMessage;
+  let messageToSend = { message: 'Test Private Message' };
+
+  beforeEach(async () => {
+    userToSendMessage = await generateUser();
+  });
+
+  it('returns error when message is not provided', async () => {
+    await expect(userToSendMessage.post('/send-private-message'))
+      .to.eventually.be.rejected.and.eql({
+        code: 400,
+        error: 'BadRequest',
+        message: 'Invalid request parameters.',
+      });
+  });
+
+  it('returns error when toUserId is not provided', async () => {
+    await expect(userToSendMessage.post('/send-private-message', {
+      message: messageToSend,
+    })).to.eventually.be.rejected.and.eql({
+      code: 400,
+      error: 'BadRequest',
+      message: 'Invalid request parameters.',
+    });
+  });
+
+  it('returns error when to user is not found', async () => {
+    await expect(userToSendMessage.post('/send-private-message', {
+      message: messageToSend,
+      toUserId: generateUUID(),
+    })).to.eventually.be.rejected.and.eql({
+      code: 404,
+      error: 'NotFound',
+      message: t('userNotFound'),
+    });
+  });
+
+  it('returns error when to user has blocked the sender', async () => {
+    let receiver = await generateUser({'inbox.blocks': [userToSendMessage._id]});
+
+    await expect(userToSendMessage.post('/send-private-message', {
+      message: messageToSend,
+      toUserId: receiver._id,
+    })).to.eventually.be.rejected.and.eql({
+      code: 401,
+      error: 'NotAuthorized',
+      message: t('notAuthorizedToSendMessageToThisUser'),
+    });
+  });
+
+  it('returns error when sender has blocked to user', async () => {
+    let receiver = await generateUser();
+    let sender = await generateUser({'inbox.blocks': [receiver._id]});
+
+    await expect(sender.post('/send-private-message', {
+      message: messageToSend,
+      toUserId: receiver._id,
+    })).to.eventually.be.rejected.and.eql({
+      code: 401,
+      error: 'NotAuthorized',
+      message: t('notAuthorizedToSendMessageToThisUser'),
+    });
+  });
+
+  it('returns error when to user has opted out of messaging', async () => {
+    let receiver = await generateUser({'inbox.optOut': true});
+
+    await expect(userToSendMessage.post('/send-private-message', {
+      message: messageToSend,
+      toUserId: receiver._id,
+    })).to.eventually.be.rejected.and.eql({
+      code: 401,
+      error: 'NotAuthorized',
+      message: t('notAuthorizedToSendMessageToThisUser'),
+    });
+  });
+
+  it('sends a private message to a user', async () => {
+    let receiver = await generateUser();
+
+    await userToSendMessage.post('/send-private-message', {
+      message: messageToSend,
+      toUserId: receiver._id,
+    });
+
+    let updatedReceiver = await receiver.get('/user');
+    let updatedSender = await userToSendMessage.get('/user');
+
+    let sendersMessageInReceiversInbox = _.find(updatedReceiver.inbox.messages, (message) => {
+      return message.uuid === userToSendMessage._id && message.text === messageToSend.message;
+    });
+
+    let sendersMessageInSendersInbox = _.find(updatedSender.inbox.messages, (message) => {
+      return message.uuid === receiver._id && message.text === messageToSend.message;
+    });
+
+    expect(sendersMessageInReceiversInbox).to.exist;
+    expect(sendersMessageInSendersInbox).to.exist;
+  });
+
+  it('sends a private message about gems to a user', async () => {
+    let receiver = await generateUser();
+    let messageAboutGemsToSend = {
+      type: 'gems',
+      gems: {
+        amount: 2,
+      },
+      message: 'Test Message About Gems',
+    };
+
+    await userToSendMessage.post('/send-private-message', {
+      message: messageAboutGemsToSend,
+      toUserId: receiver._id,
+    });
+
+    let updatedReceiver = await receiver.get('/user');
+    let updatedSender = await userToSendMessage.get('/user');
+
+    let sendersMessageInReceiversInbox = _.find(updatedReceiver.inbox.messages, (message) => {
+      return message.uuid === userToSendMessage._id;
+    });
+
+    let sendersMessageInSendersInbox = _.find(updatedSender.inbox.messages, (message) => {
+      return message.uuid === receiver._id;
+    });
+
+    expect(sendersMessageInReceiversInbox).to.exist;
+    expect(sendersMessageInReceiversInbox.text).to.equal(`Hello ${receiver.profile.name}, ${userToSendMessage.profile.name} has sent you ${messageAboutGemsToSend.gems.amount} gems! ${messageAboutGemsToSend.message}`);
+    expect(sendersMessageInSendersInbox).to.exist;
+    expect(sendersMessageInSendersInbox.text).to.equal(`Hello ${receiver.profile.name}, ${userToSendMessage.profile.name} has sent you ${messageAboutGemsToSend.gems.amount} gems! ${messageAboutGemsToSend.message}`);
+  });
+
+  it('sends a private message about subscriptions to a user', async () => {
+    let receiver = await generateUser();
+    let messageAboutSubscriptionToSend = {
+      type: 'subscription',
+      subscription: {
+        key: 'basic_12mo',
+      },
+      message: 'Test Message About Subscription',
+    };
+
+    await userToSendMessage.post('/send-private-message', {
+      message: messageAboutSubscriptionToSend,
+      toUserId: receiver._id,
+    });
+
+    let updatedReceiver = await receiver.get('/user');
+    let updatedSender = await userToSendMessage.get('/user');
+
+    let sendersMessageInReceiversInbox = _.find(updatedReceiver.inbox.messages, (message) => {
+      return message.uuid === userToSendMessage._id;
+    });
+
+    let sendersMessageInSendersInbox = _.find(updatedSender.inbox.messages, (message) => {
+      return message.uuid === receiver._id;
+    });
+
+    expect(sendersMessageInReceiversInbox).to.exist;
+    expect(sendersMessageInReceiversInbox.text).to.equal(`Hello ${receiver.profile.name}, ${userToSendMessage.profile.name} has sent you 12 months of subscription! ${messageAboutSubscriptionToSend.message}`);
+    expect(sendersMessageInSendersInbox).to.exist;
+    expect(sendersMessageInSendersInbox.text).to.equal(`Hello ${receiver.profile.name}, ${userToSendMessage.profile.name} has sent you 12 months of subscription! ${messageAboutSubscriptionToSend.message}`);
+  });
+});
diff --git a/website/src/controllers/api-v3/members.js b/website/src/controllers/api-v3/members.js
index ad42fe5e8d..36533968d5 100644
--- a/website/src/controllers/api-v3/members.js
+++ b/website/src/controllers/api-v3/members.js
@@ -9,8 +9,13 @@ import { model as Group } from '../../models/group';
 import { model as Challenge } from '../../models/challenge';
 import {
   NotFound,
+  NotAuthorized,
 } from '../../libs/api-v3/errors';
 import * as Tasks from '../../models/task';
+import {
+  getUserInfo,
+  sendTxn as sendTxnEmail,
+} from '../../libs/api-v3/email';
 
 let api = {};
 
@@ -231,4 +236,53 @@ api.getChallengeMemberProgress = {
   },
 };
 
+/**
+ * @api {posts} /send-private-message Get a challenge member progress
+ * @apiVersion 3.0.0
+ * @apiName SendPrivateMessage
+ * @apiGroup Members
+ *
+ * @apiParam {String} message The message
+ * @apiParam {UUID} toUserId The toUser _id
+ *
+ * @apiSuccess {} Object Returns an empty object
+ */
+api.sendPrivateMessage = {
+  method: 'POST',
+  url: '/send-private-message',
+  middlewares: [authWithHeaders(), cron],
+  async handler (req, res) {
+    req.checkBody('message', res.t('messageRequired')).notEmpty();
+    req.checkBody('toUserId', res.t('toUserIDRequired')).notEmpty().isUUID();
+
+    let validationErrors = req.validationErrors();
+    if (validationErrors) throw validationErrors;
+
+    let sender = res.locals.user;
+    let message = req.body.message;
+
+    let userToReceiveMessage = await User.findById(req.body.toUserId).exec();
+    if (!userToReceiveMessage) throw new NotFound(res.t('userNotFound'));
+
+    let userBlockedSender = userToReceiveMessage.inbox.blocks.indexOf(sender._id) !== -1;
+    let userIsBlockBySender = sender.inbox.blocks.indexOf(userToReceiveMessage._id) !== -1;
+    let userOptedOutOfMessaging = userToReceiveMessage.inbox.optOut;
+
+    if (userBlockedSender || userIsBlockBySender || userOptedOutOfMessaging) {
+      throw new NotAuthorized(res.t('notAuthorizedToSendMessageToThisUser'));
+    }
+
+    await sender.sendMessage(userToReceiveMessage, message);
+
+    if (userToReceiveMessage.preferences.emailNotifications.newPM !== false) {
+      sendTxnEmail(userToReceiveMessage, 'new-pm', [
+        {name: 'SENDER', content: getUserInfo(sender, ['name']).name},
+        {name: 'PMS_INBOX_URL', content: '/#/options/groups/inbox'},
+      ]);
+    }
+
+    res.respond(200, {});
+  },
+};
+
 module.exports = api;
diff --git a/website/src/models/user.js b/website/src/models/user.js
index bd45c2a7c2..9ab410e6d3 100644
--- a/website/src/models/user.js
+++ b/website/src/models/user.js
@@ -7,6 +7,8 @@ import * as Tasks from './task';
 import Q from 'q';
 import { schema as TagSchema } from './tag';
 import baseModel from '../libs/api-v3/baseModel';
+import { chatDefaults } from './group';
+import { defaults } from 'lodash';
 // import {model as Challenge} from './challenge';
 
 let Schema = mongoose.Schema;
@@ -706,6 +708,30 @@ schema.methods.getGroups = function getUserGroups () {
   return userGroups;
 };
 
+schema.methods.sendMessage = async function sendMessage (userToReceiveMessage, messageData) {
+  let msg;
+  let sender = this;
+
+  if (!messageData.type) {
+    msg = messageData.message;
+  } else {
+    msg = `Hello ${userToReceiveMessage.profile.name }, ${sender.profile.name} has sent you `;
+    msg += messageData.type === 'gems' ?  `${messageData.gems.amount} gems! ` : `${shared.content.subscriptionBlocks[messageData.subscription.key].months} months of subscription! `;
+    msg += messageData.message;
+  }
+
+  shared.refPush(userToReceiveMessage.inbox.messages, chatDefaults(msg, sender));
+  userToReceiveMessage.inbox.newMessages++;
+  userToReceiveMessage._v++;
+  userToReceiveMessage.markModified('inbox.messages');
+
+  shared.refPush(sender.inbox.messages, defaults({sent: true}, chatDefaults(msg, userToReceiveMessage)));
+  sender.markModified('inbox.messages');
+
+  let promises = [userToReceiveMessage.save(), sender.save()];
+  await Q.all(promises);
+};
+
 export let model = mongoose.model('User', schema);
 
 // Initially export an empty object so external requires will get