diff --git a/app/controllers/dmails_controller.rb b/app/controllers/dmails_controller.rb
index 32f347476..a421c7bb1 100644
--- a/app/controllers/dmails_controller.rb
+++ b/app/controllers/dmails_controller.rb
@@ -22,7 +22,11 @@ class DmailsController < ApplicationController
   def show
     @dmail = Dmail.find(params[:id])
     check_privilege(@dmail)
-    @dmail.update!(is_read: true) if request.format.html?
+
+    if request.format.html? && @dmail.owner == CurrentUser.user
+      @dmail.update!(is_read: true)
+    end
+
     respond_with(@dmail)
   end
 
diff --git a/app/logical/danbooru/message_verifier.rb b/app/logical/danbooru/message_verifier.rb
new file mode 100644
index 000000000..602d9e71e
--- /dev/null
+++ b/app/logical/danbooru/message_verifier.rb
@@ -0,0 +1,19 @@
+module Danbooru
+  class MessageVerifier
+    attr_reader :purpose, :secret, :verifier
+
+    def initialize(purpose)
+      @purpose = purpose
+      @secret = Rails.application.key_generator.generate_key(purpose.to_s)
+      @verifier = ActiveSupport::MessageVerifier.new(secret, serializer: JSON, digest: "SHA256")
+    end
+
+    def generate(*options)
+      verifier.generate(*options, purpose: purpose)
+    end
+
+    def verified(*options)
+      verifier.verified(*options, purpose: purpose)
+    end
+  end
+end
diff --git a/app/models/dmail.rb b/app/models/dmail.rb
index 956fc022e..eb9c81ab8 100644
--- a/app/models/dmail.rb
+++ b/app/models/dmail.rb
@@ -148,6 +148,25 @@ class Dmail < ApplicationRecord
     end
   end
 
+  concerning :AuthorizationMethods do
+    def verifier
+      @verifier ||= Danbooru::MessageVerifier.new(:dmail_link)
+    end
+
+    def key
+      verifier.generate(id)
+    end
+
+    def valid_key?(key)
+      decoded_id = verifier.verified(key)
+      id == decoded_id
+    end
+
+    def visible_to?(user, key)
+      owner_id == user.id || valid_key?(key)
+    end
+  end
+
   include AddressMethods
   include FactoryMethods
   extend SearchMethods
@@ -193,15 +212,6 @@ class Dmail < ApplicationRecord
     end
   end
 
-  def key
-    verifier = ActiveSupport::MessageVerifier.new(Danbooru.config.email_key, serializer: JSON, digest: "SHA256")
-    verifier.generate("#{title} #{body}")
-  end
-
-  def visible_to?(user, key)
-    owner_id == user.id || (user.is_moderator? && key == self.key)
-  end
-
   def reportable_by?(user)
     is_recipient? && !is_automated? && !from.is_moderator?
   end
diff --git a/app/views/dmails/show.html.erb b/app/views/dmails/show.html.erb
index 0bd18b085..6741660d1 100644
--- a/app/views/dmails/show.html.erb
+++ b/app/views/dmails/show.html.erb
@@ -27,7 +27,7 @@
       <p>
         <%= link_to "Respond", new_dmail_path(:respond_to_id => @dmail) %>
         | <%= link_to "Forward", new_dmail_path(:respond_to_id => @dmail, :forward => true) %>
-        | <%= link_to "Permalink", dmail_path(@dmail, :key => @dmail.key), :title => "Use this URL to privately share with a moderator" %>
+        | <%= link_to "Share", dmail_path(@dmail, key: @dmail.key), title: "Anyone with this link will be able to view this dmail." %>
         <% if @dmail.is_spam? %>
           | <%= link_to "Not spam", dmail_path(@dmail, format: :js), remote: :true, method: :put, "data-params": "dmail[is_spam]=false" %>
         <% else %>
diff --git a/test/functional/dmails_controller_test.rb b/test/functional/dmails_controller_test.rb
index eb2942003..d3b756538 100644
--- a/test/functional/dmails_controller_test.rb
+++ b/test/functional/dmails_controller_test.rb
@@ -79,6 +79,16 @@ class DmailsControllerTest < ActionDispatch::IntegrationTest
         assert_response(403)
       end
 
+      should "show dmails not owned by the current user when given a valid key" do
+        get_auth dmail_path(@dmail, key: @dmail.key), @unrelated_user
+        assert_response :success
+      end
+
+      should "not show dmails not owned by the current user when given an invalid key" do
+        get_auth dmail_path(@dmail, key: @dmail.key + "blah"), @unrelated_user
+        assert_response 403
+      end
+
       should "mark dmails as read" do
         assert_equal(false, @dmail.is_read)
         get_auth dmail_path(@dmail), @dmail.owner
@@ -94,6 +104,14 @@ class DmailsControllerTest < ActionDispatch::IntegrationTest
         assert_response :success
         assert_equal(false, @dmail.reload.is_read)
       end
+
+      should "not mark dmails as read when viewing dmails owned by another user" do
+        assert_equal(false, @dmail.is_read)
+        get_auth dmail_path(@dmail, key: @dmail.key), @unrelated_user
+
+        assert_response :success
+        assert_equal(false, @dmail.reload.is_read)
+      end
     end
 
     context "create action" do