diff --git a/app/models/canonical_email_block.rb b/app/models/canonical_email_block.rb
index a8546d65a..be8c45bfe 100644
--- a/app/models/canonical_email_block.rb
+++ b/app/models/canonical_email_block.rb
@@ -15,7 +15,7 @@ class CanonicalEmailBlock < ApplicationRecord
 
   belongs_to :reference_account, class_name: 'Account'
 
-  validates :canonical_email_hash, presence: true
+  validates :canonical_email_hash, presence: true, uniqueness: true
 
   def email=(email)
     self.canonical_email_hash = email_to_canonical_email_hash(email)
diff --git a/spec/models/account_spec.rb b/spec/models/account_spec.rb
index 03d6f5fb0..65e6714c0 100644
--- a/spec/models/account_spec.rb
+++ b/spec/models/account_spec.rb
@@ -5,6 +5,37 @@ RSpec.describe Account, type: :model do
     let(:bob) { Fabricate(:account, username: 'bob') }
     subject { Fabricate(:account) }
 
+    describe '#suspend!' do
+      it 'marks the account as suspended' do
+        subject.suspend!
+        expect(subject.suspended?).to be true
+      end
+
+      it 'creates a deletion request' do
+        subject.suspend!
+        expect(AccountDeletionRequest.where(account: subject).exists?).to be true
+      end
+
+      context 'when the account is of a local user' do
+        let!(:subject) { Fabricate(:account, user: Fabricate(:user, email: 'foo+bar@domain.org')) }
+
+        it 'creates a canonical domain block' do
+          subject.suspend!
+          expect(CanonicalEmailBlock.block?(subject.user_email)).to be true
+        end
+
+        context 'when a canonical domain block already exists for that email' do
+          before do
+            Fabricate(:canonical_email_block, email: subject.user_email)
+          end
+
+          it 'does not raise an error' do
+            expect { subject.suspend! }.not_to raise_error
+          end
+        end
+      end
+    end
+
     describe '#follow!' do
       it 'creates a follow' do
         follow = subject.follow!(bob)