diff --git a/app/jobs/regular/group_smtp_email.rb b/app/jobs/regular/group_smtp_email.rb
index 7f54d27ddde..2e31d5d548b 100644
--- a/app/jobs/regular/group_smtp_email.rb
+++ b/app/jobs/regular/group_smtp_email.rb
@@ -10,9 +10,23 @@ module Jobs
       group = Group.find_by(id: args[:group_id])
       post = Post.find_by(id: args[:post_id])
       email = args[:email]
-      recipient_user = ::UserEmail.find_by(email: email, primary: true)&.user
 
-      Rails.logger.debug("[IMAP] Sending email for group #{group.name} and post #{post.id}")
+      # There is a rare race condition causing the Imap::Sync class to create
+      # an incoming email and associated post/topic, which then kicks off
+      # the PostAlerter to notify others in the PM about a reply in the topic,
+      # but for the OP which is not necessary (because the person emailing the
+      # IMAP inbox already knows about the OP)
+      #
+      # Basically, we should never be sending this notification for the first
+      # post in a topic.
+      if post.is_first_post?
+        ImapSyncLog.warn("Aborting SMTP email for post #{post.id} in topic #{post.topic_id} to #{email}, the post is the OP and should not send an email.", group)
+        return
+      end
+
+      ImapSyncLog.debug("Sending SMTP email for post #{post.id} in topic #{post.topic_id} to #{email}.", group)
+
+      recipient_user = ::UserEmail.find_by(email: email, primary: true)&.user
       message = GroupSmtpMailer.send_mail(group, email, post)
       Email::Sender.new(message, :group_smtp, recipient_user).send
 
@@ -23,7 +37,11 @@ module Jobs
         topic_id: post.topic_id,
         post_id: post.id,
         raw: message.to_s,
-        message_id: message.message_id
+        subject: message.subject,
+        message_id: message.message_id,
+        to_addresses: message.to,
+        cc_addresses: message.cc,
+        from_address: message.from
       )
     end
   end
diff --git a/app/models/imap_sync_log.rb b/app/models/imap_sync_log.rb
index 46284a18d85..4d3809bebe9 100644
--- a/app/models/imap_sync_log.rb
+++ b/app/models/imap_sync_log.rb
@@ -12,7 +12,11 @@ class ImapSyncLog < ActiveRecord::Base
   def self.log(message, level, group_id = nil)
     now = Time.now.strftime("%Y-%m-%d %H:%M:%S.%L")
     new_log = create(message: message, level: ImapSyncLog.levels[level], group_id: group_id)
-    Rails.logger.send(level, "#{level[0].upcase}, [#{now}] [IMAP] (group_id #{group_id}) #{message}")
+    if ENV["DEBUG_IMAP"]
+      Rails.logger.send(:warn, "#{level[0].upcase}, [#{now}] [IMAP] (group_id #{group_id}) #{message}")
+    else
+      Rails.logger.send(level, "#{level[0].upcase}, [#{now}] [IMAP] (group_id #{group_id}) #{message}")
+    end
     new_log
   end
 
diff --git a/app/models/incoming_email.rb b/app/models/incoming_email.rb
index c18739ddcfa..08eb42a7477 100644
--- a/app/models/incoming_email.rb
+++ b/app/models/incoming_email.rb
@@ -28,6 +28,27 @@ class IncomingEmail < ActiveRecord::Base
       )
     SQL
   end
+
+  def to_addresses=(to)
+    if to&.is_a?(Array)
+      to = to.map(&:downcase).join(";")
+    end
+    super(to)
+  end
+
+  def cc_addresses=(cc)
+    if cc&.is_a?(Array)
+      cc = cc.map(&:downcase).join(";")
+    end
+    super(cc)
+  end
+
+  def from_address=(from)
+    if from&.is_a?(Array)
+      from = from.first
+    end
+    super(from)
+  end
 end
 
 # == Schema Information
diff --git a/lib/email/receiver.rb b/lib/email/receiver.rb
index e1aa8ea17df..50fbb219ca7 100644
--- a/lib/email/receiver.rb
+++ b/lib/email/receiver.rb
@@ -147,8 +147,8 @@ module Email
         raw: Email::Cleaner.new(@raw_email).execute,
         subject: subject,
         from_address: @from_email,
-        to_addresses: @mail.to&.map(&:downcase)&.join(";"),
-        cc_addresses: @mail.cc&.map(&:downcase)&.join(";"),
+        to_addresses: @mail.to,
+        cc_addresses: @mail.cc,
         imap_uid_validity: @opts[:imap_uid_validity],
         imap_uid: @opts[:imap_uid],
         imap_group_id: @opts[:imap_group_id],
diff --git a/lib/email/sender.rb b/lib/email/sender.rb
index b656302a692..ffd9707d328 100644
--- a/lib/email/sender.rb
+++ b/lib/email/sender.rb
@@ -173,7 +173,7 @@ module Email
         end
       end
 
-      if reply_key.present? && @message.header['Reply-To'] =~ /\<([^\>]+)\>/
+      if reply_key.present? && @message.header['Reply-To'].to_s =~ /\<([^\>]+)\>/
         email = Regexp.last_match[1]
         @message.header['List-Post'] = "<mailto:#{email}>"
       end
diff --git a/spec/jobs/regular/group_smtp_email_spec.rb b/spec/jobs/regular/group_smtp_email_spec.rb
index 606cd4e087b..a67f56dbf3d 100644
--- a/spec/jobs/regular/group_smtp_email_spec.rb
+++ b/spec/jobs/regular/group_smtp_email_spec.rb
@@ -3,13 +3,18 @@
 require 'rails_helper'
 
 RSpec.describe Jobs::GroupSmtpEmail do
-  let(:post) { Fabricate(:post) }
-  let(:group) { Fabricate(:imap_group) }
-  let!(:recipient_user) { Fabricate(:user, email: "test@test.com") }
+  fab!(:post) do
+    topic = Fabricate(:topic)
+    Fabricate(:post, topic: topic)
+    Fabricate(:post, topic: topic)
+  end
+  fab!(:group) { Fabricate(:imap_group) }
+  fab!(:recipient_user) { Fabricate(:user, email: "test@test.com") }
+  let(:post_id) { post.id }
   let(:args) do
     {
       group_id: group.id,
-      post_id: post.id,
+      post_id: post_id,
       email: "test@test.com"
     }
   end
@@ -32,7 +37,7 @@ RSpec.describe Jobs::GroupSmtpEmail do
     subject.execute(args)
     incoming = IncomingEmail.find_by(post_id: post.id, user_id: post.user_id, topic_id: post.topic_id)
     expect(incoming).not_to eq(nil)
-    expect(incoming.message_id).to eq("topic/#{post.topic_id}@test.localhost")
+    expect(incoming.message_id).to eq("topic/#{post.topic_id}/#{post.id}@test.localhost")
   end
 
   it "creates a PostReplyKey and correctly uses it for the email reply_key substitution" do
@@ -42,4 +47,19 @@ RSpec.describe Jobs::GroupSmtpEmail do
     expect(post_reply_key).not_to eq(nil)
     expect(incoming.raw).to include("Reply-To: Discourse <test+#{post_reply_key.reply_key}@incoming.com>")
   end
+
+  it "has the from_address and the to_addresses and subject filled in correctly" do
+    subject.execute(args)
+    incoming = IncomingEmail.find_by(post_id: post.id, user_id: post.user_id, topic_id: post.topic_id)
+    expect(incoming.to_addresses).to eq("test@test.com")
+    expect(incoming.subject).to include("Re: This is a test topic")
+    expect(incoming.from_address).to eq("discourseteam@ponyexpress.com")
+  end
+
+  context "when the post in the argument is the OP" do
+    let(:post_id) { post.topic.posts.first.id }
+    it "aborts and does not send a group SMTP email; the OP is the one that sent the email in the first place" do
+      expect { subject.execute(args) }.not_to(change { IncomingEmail.count })
+    end
+  end
 end