diff --git a/Changelog.md b/Changelog.md
index 0005cad8d..14cfb2502 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -37,6 +37,7 @@ Note: Although this is a minor release, the configuration file changed because t
 * Add support for setting BOSH access protocol via chat configuration [#7100](https://github.com/diaspora/diaspora/pull/7100)
 * Add number of unreviewed reports to admin dashboard and admin sidebar [#7109](https://github.com/diaspora/diaspora/pull/7109)
 * Don't federate to pods that have been offline for an extended period of time [#7120](https://github.com/diaspora/diaspora/pull/7120)
+* Add In-Reply-To and References headers to notification mails [#7122](https://github.com/diaspora/diaspora/pull/7122)
 
 # 0.6.0.1
 
diff --git a/app/mailers/notification_mailers/also_commented.rb b/app/mailers/notification_mailers/also_commented.rb
index 15914d25a..aa063cfa8 100644
--- a/app/mailers/notification_mailers/also_commented.rb
+++ b/app/mailers/notification_mailers/also_commented.rb
@@ -8,6 +8,7 @@ module NotificationMailers
 
       if mail?
         @headers[:from] = "\"#{@comment.author_name} (diaspora*)\" <#{AppConfig.mail.sender_address}>"
+        @headers[:in_reply_to] = @headers[:references] = "<#{@comment.parent.guid}@#{AppConfig.pod_uri.host}>"
         if @comment.public?
           @headers[:subject] = "Re: #{@comment.comment_email_subject}"
         else
diff --git a/app/mailers/notification_mailers/comment_on_post.rb b/app/mailers/notification_mailers/comment_on_post.rb
index 1ad0a5f0f..4782f52b2 100644
--- a/app/mailers/notification_mailers/comment_on_post.rb
+++ b/app/mailers/notification_mailers/comment_on_post.rb
@@ -6,6 +6,7 @@ module NotificationMailers
       @comment = Comment.find(comment_id)
 
       @headers[:from] = "\"#{@comment.author_name} (diaspora*)\" <#{AppConfig.mail.sender_address}>"
+      @headers[:in_reply_to] = @headers[:references] = "<#{@comment.parent.guid}@#{AppConfig.pod_uri.host}>"
       if @comment.public?
         @headers[:subject] = "Re: #{@comment.comment_email_subject}"
       else
diff --git a/app/mailers/notification_mailers/liked.rb b/app/mailers/notification_mailers/liked.rb
index 54e89ef90..c9067bf74 100644
--- a/app/mailers/notification_mailers/liked.rb
+++ b/app/mailers/notification_mailers/liked.rb
@@ -7,6 +7,7 @@ module NotificationMailers
       @like = Like.find(like_id)
 
       @headers[:subject] = I18n.t('notifier.liked.liked', :name => @sender.name)
+      @headers[:in_reply_to] = @headers[:references] = "<#{@like.parent.guid}@#{AppConfig.pod_uri.host}>"
     end
   end
 end
diff --git a/app/mailers/notification_mailers/mentioned.rb b/app/mailers/notification_mailers/mentioned.rb
index dc64f65b0..a06c82e75 100644
--- a/app/mailers/notification_mailers/mentioned.rb
+++ b/app/mailers/notification_mailers/mentioned.rb
@@ -7,6 +7,7 @@ module NotificationMailers
       @post = Mention.find_by_id(target_id).post
 
       @headers[:subject] = I18n.t('notifier.mentioned.subject', :name => @sender.name)
+      @headers[:in_reply_to] = @headers[:references] = "<#{@post.guid}@#{AppConfig.pod_uri.host}>"
     end
   end
 end
diff --git a/app/mailers/notification_mailers/private_message.rb b/app/mailers/notification_mailers/private_message.rb
index ed40e70dd..9cbe71dc3 100644
--- a/app/mailers/notification_mailers/private_message.rb
+++ b/app/mailers/notification_mailers/private_message.rb
@@ -9,6 +9,7 @@ module NotificationMailers
 
       @headers[:from] = "\"#{@message.author_name} (diaspora*)\" <#{AppConfig.mail.sender_address}>"
       @headers[:subject] = I18n.t("notifier.private_message.subject")
+      @headers[:in_reply_to] = @headers[:references] = "<#{@conversation.guid}@#{AppConfig.pod_uri.host}>"
     end
   end
 end
diff --git a/app/mailers/notification_mailers/reshared.rb b/app/mailers/notification_mailers/reshared.rb
index 4ea24e13d..e98b986ab 100644
--- a/app/mailers/notification_mailers/reshared.rb
+++ b/app/mailers/notification_mailers/reshared.rb
@@ -1,13 +1,14 @@
 module NotificationMailers
   class Reshared < NotificationMailers::Base
     attr_accessor :reshare
-    
+
     delegate :root, to: :reshare, prefix: true
 
     def set_headers(reshare_id)
       @reshare = Reshare.find(reshare_id)
 
       @headers[:subject] = I18n.t('notifier.reshared.reshared', :name => @sender.name)
+      @headers[:in_reply_to] = @headers[:references] = "<#{@reshare.root_guid}@#{AppConfig.pod_uri.host}>"
     end
   end
 end
diff --git a/spec/mailers/notifier_spec.rb b/spec/mailers/notifier_spec.rb
index 3669fddd9..f56b27c00 100644
--- a/spec/mailers/notifier_spec.rb
+++ b/spec/mailers/notifier_spec.rb
@@ -94,6 +94,11 @@ describe Notifier, type: :mailer do
       expect(@mail.subject).to include(@post.author.name)
     end
 
+    it "IN-REPLY-TO and REFERENCES: references the mentioning post" do
+      expect(@mail.in_reply_to).to eq("#{@post.guid}@#{AppConfig.pod_uri.host}")
+      expect(@mail.references).to eq("#{@post.guid}@#{AppConfig.pod_uri.host}")
+    end
+
     it "has the post text in the body" do
       expect(@mail.body.encoded).to include(@post.text)
     end
@@ -170,6 +175,11 @@ describe Notifier, type: :mailer do
       expect(@mail.to).to eq([alice.email])
     end
 
+    it "IN-REPLY-TO and REFERENCES: references the reshared post" do
+      expect(@mail.in_reply_to).to eq("#{@post.guid}@#{AppConfig.pod_uri.host}")
+      expect(@mail.references).to eq("#{@post.guid}@#{AppConfig.pod_uri.host}")
+    end
+
     it "BODY: contains the truncated original post" do
       expect(@mail.body.encoded).to include(@post.message.plain_text)
     end
@@ -216,6 +226,11 @@ describe Notifier, type: :mailer do
       expect(@mail.subject).not_to include(@cnv.subject)
     end
 
+    it "IN-REPLY-TO and REFERENCES: references the containing conversation" do
+      expect(@mail.in_reply_to).to eq("#{@cnv.guid}@#{AppConfig.pod_uri.host}")
+      expect(@mail.references).to eq("#{@cnv.guid}@#{AppConfig.pod_uri.host}")
+    end
+
     it "BODY: does not contain the message text" do
       expect(@mail.body.encoded).not_to include(@cnv.messages.first.text)
     end
@@ -290,6 +305,11 @@ describe Notifier, type: :mailer do
         expect(comment_mail.subject).to eq("Re: Headline")
       end
 
+      it "IN-REPLY-TO and REFERENCES: references the commented post" do
+        expect(comment_mail.in_reply_to).to eq("#{comment.parent.guid}@#{AppConfig.pod_uri.host}")
+        expect(comment_mail.references).to eq("#{comment.parent.guid}@#{AppConfig.pod_uri.host}")
+      end
+
       context "BODY" do
         it "contains the comment" do
           expect(comment_mail.body.encoded).to include(comment.text)
@@ -365,6 +385,11 @@ describe Notifier, type: :mailer do
           expect(mail.subject).not_to include("Limited headline")
         end
 
+        it "IN-REPLY-TO and REFERENCES: references the commented post" do
+          expect(mail.in_reply_to).to eq("#{comment.parent.guid}@#{AppConfig.pod_uri.host}")
+          expect(mail.references).to eq("#{comment.parent.guid}@#{AppConfig.pod_uri.host}")
+        end
+
         it "BODY: does not show the limited post" do
           expect(mail.body.encoded).not_to include("Limited headline")
         end
@@ -391,6 +416,11 @@ describe Notifier, type: :mailer do
         expect(mail.subject).not_to include("Limited headline")
       end
 
+      it "IN-REPLY-TO and REFERENCES: references the liked post" do
+        expect(mail.in_reply_to).to eq("#{like.parent.guid}@#{AppConfig.pod_uri.host}")
+        expect(mail.references).to eq("#{like.parent.guid}@#{AppConfig.pod_uri.host}")
+      end
+
       it "BODY: does not show the limited post" do
         expect(mail.body.encoded).not_to include("Limited headline")
       end