diff --git a/app/models/campaign.rb b/app/models/campaign.rb
index 1103e8fb2..f937b1d71 100644
--- a/app/models/campaign.rb
+++ b/app/models/campaign.rb
@@ -38,6 +38,7 @@ class Campaign < ApplicationRecord
   validate :validate_url
   validate :prevent_completed_campaign_from_update, on: :update
   validate :sender_must_belong_to_account
+  validate :inbox_must_belong_to_account
 
   belongs_to :account
   belongs_to :inbox
@@ -92,6 +93,14 @@ class Campaign < ApplicationRecord
     errors.add(:url, 'invalid') if inbox.inbox_type == 'Website' && !use_http_protocol
   end
 
+  def inbox_must_belong_to_account
+    return unless inbox
+
+    return if inbox.account_id == account_id
+
+    errors.add(:inbox_id, 'must belong to the same account as the campaign')
+  end
+
   def sender_must_belong_to_account
     return unless sender
 
diff --git a/spec/controllers/api/v1/accounts/campaigns_controller_spec.rb b/spec/controllers/api/v1/accounts/campaigns_controller_spec.rb
index 1d9908652..f33a66d0a 100644
--- a/spec/controllers/api/v1/accounts/campaigns_controller_spec.rb
+++ b/spec/controllers/api/v1/accounts/campaigns_controller_spec.rb
@@ -15,7 +15,8 @@ RSpec.describe 'Campaigns API', type: :request do
     context 'when it is an authenticated user' do
       let(:agent) { create(:user, account: account, role: :agent) }
       let(:administrator) { create(:user, account: account, role: :administrator) }
-      let!(:campaign) { create(:campaign, account: account, trigger_rules: { url: 'https://test.com' }) }
+      let(:inbox) { create(:inbox, account: account) }
+      let!(:campaign) { create(:campaign, account: account, inbox: inbox, trigger_rules: { url: 'https://test.com' }) }
 
       it 'returns unauthorized for agents' do
         get "/api/v1/accounts/#{account.id}/campaigns",
@@ -128,7 +129,7 @@ RSpec.describe 'Campaigns API', type: :request do
 
       it 'creates a new oneoff campaign' do
         twilio_sms = create(:channel_twilio_sms, account: account)
-        twilio_inbox = create(:inbox, channel: twilio_sms)
+        twilio_inbox = create(:inbox, channel: twilio_sms, account: account)
         label1 = create(:label, account: account)
         label2 = create(:label, account: account)
         scheduled_at = 2.days.from_now
diff --git a/spec/jobs/campaigns/trigger_oneoff_campaign_job_spec.rb b/spec/jobs/campaigns/trigger_oneoff_campaign_job_spec.rb
index dc8823efc..ab89f2bb5 100644
--- a/spec/jobs/campaigns/trigger_oneoff_campaign_job_spec.rb
+++ b/spec/jobs/campaigns/trigger_oneoff_campaign_job_spec.rb
@@ -2,12 +2,14 @@ require 'rails_helper'
 
 RSpec.describe Campaigns::TriggerOneoffCampaignJob do
   let(:account) { create(:account) }
-  let!(:twilio_sms) { create(:channel_twilio_sms) }
-  let!(:twilio_inbox) { create(:inbox, channel: twilio_sms) }
+  let!(:twilio_sms) { create(:channel_twilio_sms, account: account) }
+  let!(:twilio_inbox) { create(:inbox, channel: twilio_sms, account: account) }
   let(:label1) { create(:label, account: account) }
   let(:label2) { create(:label, account: account) }
 
-  let!(:campaign) { create(:campaign, inbox: twilio_inbox, audience: [{ type: 'Label', id: label1.id }, { type: 'Label', id: label2.id }]) }
+  let!(:campaign) do
+    create(:campaign, inbox: twilio_inbox, account: account, audience: [{ type: 'Label', id: label1.id }, { type: 'Label', id: label2.id }])
+  end
 
   it 'enqueues the job' do
     expect { described_class.perform_later(campaign) }.to have_enqueued_job(described_class)
diff --git a/spec/jobs/trigger_scheduled_items_job_spec.rb b/spec/jobs/trigger_scheduled_items_job_spec.rb
index ec1f72015..4409e7ee0 100644
--- a/spec/jobs/trigger_scheduled_items_job_spec.rb
+++ b/spec/jobs/trigger_scheduled_items_job_spec.rb
@@ -36,12 +36,12 @@ RSpec.describe TriggerScheduledItemsJob do
   end
 
   context 'when unexecuted Scheduled campaign jobs' do
-    let!(:twilio_sms) { create(:channel_twilio_sms) }
-    let!(:twilio_inbox) { create(:inbox, channel: twilio_sms) }
+    let!(:twilio_sms) { create(:channel_twilio_sms, account: account) }
+    let!(:twilio_inbox) { create(:inbox, channel: twilio_sms, account: account) }
 
     it 'triggers Campaigns::TriggerOneoffCampaignJob' do
-      campaign = create(:campaign, inbox: twilio_inbox)
-      create(:campaign, inbox: twilio_inbox, scheduled_at: 10.days.after)
+      campaign = create(:campaign, inbox: twilio_inbox, account: account)
+      create(:campaign, inbox: twilio_inbox, account: account, scheduled_at: 10.days.after)
       expect(Campaigns::TriggerOneoffCampaignJob).to receive(:perform_later).with(campaign).once
       described_class.perform_now
     end
diff --git a/spec/models/campaign_spec.rb b/spec/models/campaign_spec.rb
index bb03b4520..480f187f3 100644
--- a/spec/models/campaign_spec.rb
+++ b/spec/models/campaign_spec.rb
@@ -12,7 +12,7 @@ RSpec.describe Campaign do
     let(:account) { create(:account) }
     let(:website_channel) { create(:channel_widget, account: account) }
     let(:website_inbox) { create(:inbox, channel: website_channel, account: account) }
-    let(:campaign) { build(:campaign, inbox: website_inbox, display_id: nil, trigger_rules: { url: 'https://test.com' }) }
+    let(:campaign) { build(:campaign, account: account, inbox: website_inbox, display_id: nil, trigger_rules: { url: 'https://test.com' }) }
 
     before do
       campaign.save!
@@ -29,9 +29,10 @@ RSpec.describe Campaign do
       stub_request(:post, /graph.facebook.com/)
     end
 
-    let!(:facebook_channel) { create(:channel_facebook_page) }
-    let!(:facebook_inbox) { create(:inbox, channel: facebook_channel) }
-    let(:campaign) { build(:campaign, inbox: facebook_inbox) }
+    let(:account) { create(:account) }
+    let!(:facebook_channel) { create(:channel_facebook_page, account: account) }
+    let!(:facebook_inbox) { create(:inbox, channel: facebook_channel, account: account) }
+    let(:campaign) { build(:campaign, inbox: facebook_inbox, account: account) }
 
     it 'would not save the campaigns' do
       expect(campaign.save).to be false
@@ -42,7 +43,7 @@ RSpec.describe Campaign do
   context 'when a campaign is completed' do
     let(:account) { create(:account) }
     let(:web_widget) { create(:channel_widget, account: account) }
-    let!(:campaign) { create(:campaign, inbox: web_widget.inbox, campaign_status: :completed, trigger_rules: { url: 'https://test.com' }) }
+    let!(:campaign) { create(:campaign, account: account, inbox: web_widget.inbox, campaign_status: :completed, trigger_rules: { url: 'https://test.com' }) }
 
     it 'would prevent further updates' do
       campaign.title = 'new name'
@@ -63,9 +64,10 @@ RSpec.describe Campaign do
 
   describe 'ensure_correct_campaign_attributes' do
     context 'when Twilio SMS campaign' do
-      let!(:twilio_sms) { create(:channel_twilio_sms) }
-      let!(:twilio_inbox) { create(:inbox, channel: twilio_sms) }
-      let(:campaign) { build(:campaign, inbox: twilio_inbox) }
+      let(:account) { create(:account) }
+      let!(:twilio_sms) { create(:channel_twilio_sms, account: account) }
+      let!(:twilio_inbox) { create(:inbox, channel: twilio_sms, account: account) }
+      let(:campaign) { build(:campaign, account: account, inbox: twilio_inbox) }
 
       it 'only saves campaign type as oneoff and wont leave scheduled_at empty' do
         campaign.campaign_type = 'ongoing'
@@ -84,9 +86,10 @@ RSpec.describe Campaign do
     end
 
     context 'when SMS campaign' do
-      let!(:sms_channel) { create(:channel_sms) }
-      let!(:sms_inbox) { create(:inbox, channel: sms_channel) }
-      let(:campaign) { build(:campaign, inbox: sms_inbox) }
+      let(:account) { create(:account) }
+      let!(:sms_channel) { create(:channel_sms, account: account) }
+      let!(:sms_inbox) { create(:inbox, channel: sms_channel, account: account) }
+      let(:campaign) { build(:campaign, account: account, inbox: sms_inbox) }
 
       it 'only saves campaign type as oneoff and wont leave scheduled_at empty' do
         campaign.campaign_type = 'ongoing'
@@ -136,4 +139,25 @@ RSpec.describe Campaign do
       )
     end
   end
+
+  context 'when validating inbox' do
+    let(:account) { create(:account) }
+    let(:other_account) { create(:account) }
+    let(:web_widget) { create(:channel_widget, account: account) }
+    let(:inbox) { create(:inbox, channel: web_widget, account: account) }
+    let(:other_account_inbox) { create(:inbox, account: other_account) }
+
+    it 'allows inbox from the same account' do
+      campaign = build(:campaign, inbox: inbox, account: account)
+      expect(campaign).to be_valid
+    end
+
+    it 'does not allow inbox from different account' do
+      campaign = build(:campaign, inbox: other_account_inbox, account: account)
+      expect(campaign).not_to be_valid
+      expect(campaign.errors[:inbox_id]).to include(
+        'must belong to the same account as the campaign'
+      )
+    end
+  end
 end
diff --git a/spec/services/sms/oneoff_sms_campaign_service_spec.rb b/spec/services/sms/oneoff_sms_campaign_service_spec.rb
index 27492f83b..2f7e5bbf4 100644
--- a/spec/services/sms/oneoff_sms_campaign_service_spec.rb
+++ b/spec/services/sms/oneoff_sms_campaign_service_spec.rb
@@ -4,8 +4,8 @@ describe Sms::OneoffSmsCampaignService do
   subject(:sms_campaign_service) { described_class.new(campaign: campaign) }
 
   let(:account) { create(:account) }
-  let!(:sms_channel) { create(:channel_sms) }
-  let!(:sms_inbox) { create(:inbox, channel: sms_channel) }
+  let!(:sms_channel) { create(:channel_sms, account: account) }
+  let!(:sms_inbox) { create(:inbox, channel: sms_channel, account: account) }
   let(:label1) { create(:label, account: account) }
   let(:label2) { create(:label, account: account) }
   let!(:campaign) do
diff --git a/spec/services/twilio/oneoff_sms_campaign_service_spec.rb b/spec/services/twilio/oneoff_sms_campaign_service_spec.rb
index f85199c6e..f8858f174 100644
--- a/spec/services/twilio/oneoff_sms_campaign_service_spec.rb
+++ b/spec/services/twilio/oneoff_sms_campaign_service_spec.rb
@@ -4,8 +4,8 @@ describe Twilio::OneoffSmsCampaignService do
   subject(:sms_campaign_service) { described_class.new(campaign: campaign) }
 
   let(:account) { create(:account) }
-  let!(:twilio_sms) { create(:channel_twilio_sms) }
-  let!(:twilio_inbox) { create(:inbox, channel: twilio_sms) }
+  let!(:twilio_sms) { create(:channel_twilio_sms, account: account) }
+  let!(:twilio_inbox) { create(:inbox, channel: twilio_sms, account: account) }
   let(:label1) { create(:label, account: account) }
   let(:label2) { create(:label, account: account) }
   let!(:campaign) do