chore(email): log smtp errors

app/mailers/application_mailer.rb

@@ -6,16 +6,20 @@ class ApplicationMailer < ActionMailer::Base
   before_action :add_dolist_header
 
   # Don’t retry to send a message if the server rejects the recipient address
-  rescue_from Net::SMTPSyntaxError do |_error|
+  rescue_from Net::SMTPSyntaxError do |_exception|
     message.perform_deliveries = false
   end
 
-  rescue_from Net::SMTPServerBusy do |error|
+  rescue_from Net::SMTPServerBusy do |exception|
-    if /unexpected recipients/.match?(error.message)
+    if /unexpected recipients/.match?(exception.message)
       message.perform_deliveries = false
+    else
+      log_smtp_error(exception)
     end
   end
 
+  rescue_from Net::SMTPError, with: :log_smtp_error
+
   # Attach the procedure logo to the email (if any).
   # Returns the attachment url.
   def attach_logo(procedure)
@@ -38,4 +42,14 @@ class ApplicationMailer < ActionMailer::Base
   def add_dolist_header
     headers['X-Dolist-Message-Name'] = action_name
   end
+
+  def log_smtp_error(exception)
+    if defined?(message) && message.to.present?
+      EmailEvent.create_from_message!(message, status: "dispatch_error")
+    end
+
+    Sentry.capture_exception(exception, extra: { to: message&.to, subject: message&.subject })
+
+    # TODO find a way to re attempt the job
+  end
 end

app/models/email_event.rb

@@ -13,8 +13,10 @@
 #
 class EmailEvent < ApplicationRecord
   enum status: {
-    dispatched: 'dispatched'
+    dispatched: 'dispatched',
+    dispatch_error: 'dispatch_error'
   }
+
   class << self
     def create_from_message!(message, status:)
       message.to.each do |recipient|

spec/mailers/application_mailer_spec.rb

@@ -40,5 +40,33 @@ RSpec.describe ApplicationMailer, type: :mailer do
       expect(event.processed_at).to be_within(1.second).of(Time.zone.now)
       expect(event.status).to eq('dispatched')
     end
+
+    context "when email is not sent" do
+      subject(:send_email) { UserMailer.ask_for_merge(user1, user2.email).deliver_now }
+
+      before do
+        allow_any_instance_of(Mail::Message)
+          .to receive(:deliver)
+          .and_raise(smtp_error)
+      end
+
+      context "smtp server busy" do
+        let(:smtp_error) { Net::SMTPServerBusy.new }
+
+        it "creates an event" do
+          expect { send_email }.to change { EmailEvent.count }.by(1)
+          expect(EmailEvent.last.status).to eq('dispatch_error')
+        end
+      end
+
+      context "smtp unknown error" do
+        let(:smtp_error) { Net::SMTPUnknownError.new }
+
+        it "creates an event" do
+          expect { send_email }.to change { EmailEvent.count }.by(1)
+          expect(EmailEvent.last.status).to eq('dispatch_error')
+        end
+      end
+    end
   end
 end