diff --git a/app/api/server/v1/chat.js b/app/api/server/v1/chat.js
index 815a85f1757..6c77dd06831 100644
--- a/app/api/server/v1/chat.js
+++ b/app/api/server/v1/chat.js
@@ -128,7 +128,7 @@ API.v1.addRoute('chat.pinMessage', { authRequired: true }, {
 
 API.v1.addRoute('chat.postMessage', { authRequired: true }, {
 	post() {
-		const messageReturn = processWebhookMessage(this.bodyParams, this.user, undefined, true)[0];
+		const messageReturn = processWebhookMessage(this.bodyParams, this.user)[0];
 
 		if (!messageReturn) {
 			return API.v1.failure('unknown-error');
diff --git a/app/integrations/server/api/api.js b/app/integrations/server/api/api.js
index aa55b3bd1fa..63d32c9be33 100644
--- a/app/integrations/server/api/api.js
+++ b/app/integrations/server/api/api.js
@@ -247,7 +247,7 @@ function executeIntegrationRest() {
 	this.bodyParams.bot = { i: this.integration._id };
 
 	try {
-		const message = processWebhookMessage(this.bodyParams, this.user, defaultValues);
+		const message = processWebhookMessage(this.bodyParams, this.user, defaultValues, this.integration);
 		if (_.isEmpty(message)) {
 			return API.v1.failure('unknown-error');
 		}
diff --git a/app/integrations/server/lib/triggerHandler.js b/app/integrations/server/lib/triggerHandler.js
index eca745531fa..7ce09dc03f8 100644
--- a/app/integrations/server/lib/triggerHandler.js
+++ b/app/integrations/server/lib/triggerHandler.js
@@ -205,7 +205,7 @@ integrations.triggerHandler = new class RocketChatIntegrationHandler {
 			message.channel = `#${ tmpRoom._id }`;
 		}
 
-		message = processWebhookMessage(message, user, defaultValues);
+		message = processWebhookMessage(message, user, defaultValues, trigger);
 		return message;
 	}
 
diff --git a/app/lib/server/functions/processWebhookMessage.js b/app/lib/server/functions/processWebhookMessage.js
index 3fcfa34b866..63eeeb16252 100644
--- a/app/lib/server/functions/processWebhookMessage.js
+++ b/app/lib/server/functions/processWebhookMessage.js
@@ -1,14 +1,21 @@
 import { Meteor } from 'meteor/meteor';
 import _ from 'underscore';
 import s from 'underscore.string';
+import mem from 'mem';
 
 import { getRoomByNameOrIdWithOptionToJoin } from './getRoomByNameOrIdWithOptionToJoin';
 import { sendMessage } from './sendMessage';
 import { validateRoomMessagePermissions } from '../../../authorization/server/functions/canSendMessage';
-import { Subscriptions } from '../../../models';
 import { getDirectMessageByIdWithOptionToJoin, getDirectMessageByNameOrIdWithOptionToJoin } from './getDirectMessageByNameOrIdWithOptionToJoin';
 
-export const processWebhookMessage = function(messageObj, user, defaultValues = { channel: '', alias: '', avatar: '', emoji: '' }, mustBeJoined = false) {
+// show deprecation warning only once per hour for each integration
+const showDeprecation = mem(({ integration, channels, username }, error) => {
+	console.warn(`Warning: The integration "${ integration }" failed to send a message to "${ [].concat(channels).join(',') }" because user "${ username }" doesn't have permission or is not a member of the channel.`);
+	console.warn('This behavior is deprecated and starting from version v4.0.0 the following error will be thrown and the message will not be sent.');
+	console.error(error);
+}, { maxAge: 360000, cacheKey: (integration) => JSON.stringify(integration) });
+
+export const processWebhookMessage = function(messageObj, user, defaultValues = { channel: '', alias: '', avatar: '', emoji: '' }, integration = null) {
 	const sentData = [];
 	const channels = [].concat(messageObj.channel || messageObj.roomId || defaultValues.channel);
 
@@ -44,12 +51,7 @@ export const processWebhookMessage = function(messageObj, user, defaultValues =
 				throw new Meteor.Error('invalid-channel');
 		}
 
-		if (mustBeJoined && !Subscriptions.findOneByRoomIdAndUserId(room._id, user._id, { fields: { _id: 1 } })) {
-			// throw new Meteor.Error('invalid-room', 'Invalid room provided to send a message to, must be joined.');
-			throw new Meteor.Error('invalid-channel'); // Throwing the generic one so people can't "brute force" find rooms
-		}
-
-		if (messageObj.attachments && !_.isArray(messageObj.attachments)) {
+		if (messageObj.attachments && !Array.isArray(messageObj.attachments)) {
 			console.log('Attachments should be Array, ignoring value'.red, messageObj.attachments);
 			messageObj.attachments = undefined;
 		}
@@ -84,7 +86,18 @@ export const processWebhookMessage = function(messageObj, user, defaultValues =
 			}
 		}
 
-		validateRoomMessagePermissions(room, { uid: user._id, ...user });
+		try {
+			validateRoomMessagePermissions(room, { uid: user._id, ...user });
+		} catch (error) {
+			if (!integration) {
+				throw error;
+			}
+			showDeprecation({
+				integration: integration.name,
+				channels: integration.channel,
+				username: integration.username,
+			}, error);
+		}
 
 		const messageReturn = sendMessage(user, message, room);
 		sentData.push({ channel, message: messageReturn });