diff --git a/app/controllers/admin/email_templates_controller.rb b/app/controllers/admin/email_templates_controller.rb
index d3d1e963289..2c3e44610db 100644
--- a/app/controllers/admin/email_templates_controller.rb
+++ b/app/controllers/admin/email_templates_controller.rb
@@ -15,6 +15,7 @@ class Admin::EmailTemplatesController < Admin::AdminController
                      "system_messages.email_reject_reply_key", "system_messages.email_reject_topic_closed",
                      "system_messages.email_reject_topic_not_found",
                      "system_messages.email_reject_screened_email",
+                     "system_messages.email_reject_unrecognized_error",
                      "system_messages.pending_users_reminder", "system_messages.post_hidden",
                      "system_messages.restore_failed", "system_messages.restore_succeeded",
                      "system_messages.spam_post_blocked", "system_messages.too_many_spam_flags",
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 2fc2c220cc8..65fd41b488f 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -2269,6 +2269,14 @@ en:
 
         Your email was marked as "auto generated", which means it was automatically created by a computer instead of being typed by a human; we can't accept those kinds of emails. If you believe this is an error, contact a staff member.
 
+    email_reject_unrecognized_error:
+      title: "Email Reject Unrecognized Error"
+      subject_template: "[%{email_prefix}] Email issue -- Unrecognized Error"
+      text_body_template: |
+        We're sorry, but your email message to %{destination} (titled %{former_title}) didn't work.
+
+        There was an unrecognized error while processing your email and it wasn't posted. You should try again, or contact a staff member.
+
     email_error_notification:
       title: "Email Error Notification"
       subject_template: "[%{email_prefix}] Email issue -- POP authentication error"
diff --git a/lib/email/processor.rb b/lib/email/processor.rb
index 71c9b846f70..a477f58e490 100644
--- a/lib/email/processor.rb
+++ b/lib/email/processor.rb
@@ -52,6 +52,7 @@ module Email
         when ActiveRecord::Rollback                       then :email_reject_invalid_post
         when Email::Receiver::InvalidPostAction           then :email_reject_invalid_post_action
         when Discourse::InvalidAccess                     then :email_reject_invalid_access
+        else                                                   :email_reject_unrecognized_error
       end
 
       template_args = {}
@@ -63,6 +64,14 @@ module Email
         template_args[:post_error] = e.message
       end
 
+      if message_template == :email_reject_unrecognized_error
+        msg  = "Unrecognized error type (#{e.class}: #{e.message}) when processing incoming email"
+        msg += "\n\nBacktrace:\n#{e.backtrace.map { |l| "  #{l}" }.join("\n")}"
+        msg += "\n\nMail:\n#{mail_string}"
+
+        Rails.logger.error(msg)
+      end
+
       if message_template
         # inform the user about the rejection
         message = Mail::Message.new(mail_string)
@@ -76,18 +85,14 @@ module Email
         if can_send_rejection_email?(message.from, message_template)
           Email::Sender.new(client_message, message_template).send
         end
-      else
-        msg  = "Unrecognized error type (#{e.class}: #{e.message}) when processing incoming email"
-        msg += "\n\nBacktrace:\n#{e.backtrace.map { |l| "  #{l}" }.join("\n")}"
-        msg += "\n\nMail:\n#{mail_string}"
-
-        Rails.logger.error(msg)
       end
 
       client_message
     end
 
     def can_send_rejection_email?(email, type)
+      return true if type == :email_reject_unrecognized_error
+
       key = "rejection_email:#{email}:#{type}:#{Date.today}"
 
       if $redis.setnx(key, "1")
diff --git a/spec/components/email/processor_spec.rb b/spec/components/email/processor_spec.rb
index c30b09ad4ee..b99ae784108 100644
--- a/spec/components/email/processor_spec.rb
+++ b/spec/components/email/processor_spec.rb
@@ -3,9 +3,11 @@ require "email/processor"
 
 describe Email::Processor do
 
+  let(:from) { "foo@bar.com" }
+
   describe "rate limits" do
 
-    let(:mail) { "From: foo@bar.com\nTo: bar@foo.com\nSubject: FOO BAR\n\nFoo foo bar bar?" }
+    let(:mail) { "From: #{from}\nTo: bar@foo.com\nSubject: FOO BAR\n\nFoo foo bar bar?" }
     let(:limit_exceeded) { RateLimiter::LimitExceeded.new(10) }
 
     before do
@@ -24,4 +26,64 @@ describe Email::Processor do
 
   end
 
+  context "known error" do
+
+    let(:mail) { "From: #{from}\nTo: bar@foo.com" }
+    let(:mail2) { "From: #{from}\nTo: foo@foo.com" }
+    let(:mail3) { "From: #{from}\nTo: foobar@foo.com" }
+
+    it "only sends one rejection email per day" do
+      key = "rejection_email:#{[from]}:email_reject_empty:#{Date.today}"
+      $redis.expire(key, 0)
+
+      expect {
+        Email::Processor.process!(mail)
+      }.to change { EmailLog.count }.by(1)
+
+      expect {
+        Email::Processor.process!(mail2)
+      }.to change { EmailLog.count }.by(0)
+
+      Timecop.freeze(Date.today + 1)
+      key = "rejection_email:#{[from]}:email_reject_empty:#{Date.today}"
+      $redis.expire(key, 0)
+
+      expect {
+        Email::Processor.process!(mail3)
+      }.to change { EmailLog.count }.by(1)
+    end
+  end
+
+  context "unrecognized error" do
+
+    let(:mail) { "From: #{from}\nTo: bar@foo.com\nSubject: FOO BAR\n\nFoo foo bar bar?" }
+    let(:mail2) { "From: #{from}\nTo: foo@foo.com\nSubject: BAR BAR\n\nBar bar bar bar?" }
+
+    it "sends a rejection email on an unrecognized error" do
+      Email::Processor.any_instance.stubs(:can_send_rejection_email?).returns(true)
+      Email::Receiver.any_instance.stubs(:process_internal).raises("boom")
+      Rails.logger.expects(:error)
+
+      Email::Processor.process!(mail)
+      expect(IncomingEmail.first.error).to             eq("boom")
+      expect(IncomingEmail.first.rejection_message).to be_present
+      expect(EmailLog.first.email_type).to             eq("email_reject_unrecognized_error")
+    end
+
+    it "sends more than one rejection email per day" do
+      Email::Receiver.any_instance.stubs(:process_internal).raises("boom")
+      key = "rejection_email:#{[from]}:email_reject_unrecognized_error:#{Date.today}"
+      $redis.expire(key, 0)
+
+      expect {
+        Email::Processor.process!(mail)
+      }.to change { EmailLog.count }.by(1)
+
+      expect {
+        Email::Processor.process!(mail2)
+      }.to change { EmailLog.count }.by(1)
+    end
+
+  end
+
 end