diff --git a/app/models/topic.rb b/app/models/topic.rb
index e373f4f4d4a..2fe7f114463 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -1892,46 +1892,6 @@ class Topic < ActiveRecord::Base
       .first
   end
 
-  def incoming_email_addresses(group: nil, received_before: Time.zone.now)
-    email_addresses = Set.new
-
-    # TODO(martin) Look at improving this N1, it will just get slower the
-    # more replies/incoming emails there are for the topic.
-    self
-      .incoming_email
-      .where("created_at <= ?", received_before)
-      .each do |incoming_email|
-        to_addresses = incoming_email.to_addresses_split
-        cc_addresses = incoming_email.cc_addresses_split
-        combined_addresses = [to_addresses, cc_addresses].flatten
-
-        # We only care about the emails addressed to the group or CC'd to the
-        # group if the group is present. If combined addresses is empty we do
-        # not need to do this check, and instead can proceed on to adding the
-        # from address.
-        #
-        # Will not include test1@gmail.com if the only IncomingEmail
-        # is:
-        #
-        # from: test1@gmail.com
-        # to: test+support@discoursemail.com
-        #
-        # Because we don't care about the from addresses and also the to address
-        # is not the email_username, which will be something like test1@gmail.com.
-        if group.present? && combined_addresses.any?
-          next if combined_addresses.none? { |address| address =~ group.email_username_regex }
-        end
-
-        email_addresses.add(incoming_email.from_address)
-        email_addresses.merge(combined_addresses)
-      end
-
-    email_addresses.subtract([nil, ""])
-    email_addresses.delete(group.email_username) if group.present?
-
-    email_addresses.to_a
-  end
-
   def create_invite_notification!(target_user, notification_type, invited_by, post_number: 1)
     if UserCommScreener.new(
          acting_user: invited_by,
diff --git a/spec/lib/email/receiver_spec.rb b/spec/lib/email/receiver_spec.rb
index 99035646be8..baf9e0dae06 100644
--- a/spec/lib/email/receiver_spec.rb
+++ b/spec/lib/email/receiver_spec.rb
@@ -1550,10 +1550,12 @@ RSpec.describe Email::Receiver do
       handler_calls = 0
       handler =
         proc do |topic|
-          expect(topic.incoming_email_addresses).to contain_exactly(
-            "discourse@bar.com",
-            "category@foo.com",
-          )
+          expect(
+            [
+              topic.incoming_email.first.from_address,
+              topic.incoming_email.first.to_addresses_split,
+            ].flatten,
+          ).to contain_exactly("discourse@bar.com", "category@foo.com")
           handler_calls += 1
         end
 
diff --git a/spec/models/topic_spec.rb b/spec/models/topic_spec.rb
index 4db4f3a5546..4dd28ebff33 100644
--- a/spec/models/topic_spec.rb
+++ b/spec/models/topic_spec.rb
@@ -3271,85 +3271,6 @@ RSpec.describe Topic do
     end
   end
 
-  describe "#incoming_email_addresses" do
-    fab!(:group) do
-      Fabricate(
-        :group,
-        smtp_server: "imap.gmail.com",
-        smtp_port: 587,
-        email_username: "discourse@example.com",
-        email_password: "discourse@example.com",
-      )
-    end
-
-    fab!(:topic) do
-      Fabricate(
-        :private_message_topic,
-        topic_allowed_groups: [Fabricate.build(:topic_allowed_group, group: group)],
-      )
-    end
-
-    let!(:incoming1) do
-      Fabricate(
-        :incoming_email,
-        to_addresses: "discourse@example.com",
-        from_address: "johnsmith@user.com",
-        topic: topic,
-        post: topic.posts.first,
-        created_at: 20.minutes.ago,
-      )
-    end
-    let!(:incoming2) do
-      Fabricate(
-        :incoming_email,
-        from_address: "discourse@example.com",
-        to_addresses: "johnsmith@user.com",
-        topic: topic,
-        post: Fabricate(:post, topic: topic),
-        created_at: 10.minutes.ago,
-      )
-    end
-    let!(:incoming3) do
-      Fabricate(
-        :incoming_email,
-        to_addresses: "discourse@example.com",
-        from_address: "johnsmith@user.com",
-        topic: topic,
-        post: topic.posts.first,
-        cc_addresses: "otherguy@user.com",
-        created_at: 2.minutes.ago,
-      )
-    end
-    let!(:incoming4) do
-      Fabricate(
-        :incoming_email,
-        to_addresses: "unrelated@test.com",
-        from_address: "discourse@example.com",
-        topic: topic,
-        post: topic.posts.first,
-        created_at: 1.minutes.ago,
-      )
-    end
-
-    it "returns an array of all the incoming email addresses" do
-      expect(topic.incoming_email_addresses).to match_array(
-        %w[discourse@example.com johnsmith@user.com otherguy@user.com unrelated@test.com],
-      )
-    end
-
-    it "returns an array of all the incoming email addresses where incoming was received before X" do
-      expect(topic.incoming_email_addresses(received_before: 5.minutes.ago)).to match_array(
-        %w[discourse@example.com johnsmith@user.com],
-      )
-    end
-
-    context "when the group is present" do
-      it "excludes incoming emails that are not to or CCd to the group" do
-        expect(topic.incoming_email_addresses(group: group)).not_to include("unrelated@test.com")
-      end
-    end
-  end
-
   describe "#cannot_permanently_delete_reason" do
     fab!(:post) { Fabricate(:post) }
     let!(:topic) { post.topic }