diff --git a/Gemfile b/Gemfile
index 7da8a4c9..28753a42 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,8 +14,8 @@ gem "administrate", "0.20.1"
 # Reduces boot times through caching; required in config/boot.rb
 gem "bootsnap", "1.18.3", require: false
 
-# Rack middleware for blocking & throttling 
-gem 'rack-attack'
+# Rack middleware for blocking & throttling
+gem "rack-attack"
 
 # Use Sass to process CSS
 # gem "sassc-rails"
@@ -73,6 +73,8 @@ gem "rack-cors", "2.0.2"
 gem "rails", "7.1.3.4"
 # Use Redis adapter to run Action Cable in production
 gem "redis", "5.2.0"
+# User resend.com to send emails
+gem "resend"
 # Sentry SDK for Rails
 gem "sentry-rails", "5.17.3"
 # Sentry SDK for Ruby
@@ -109,6 +111,8 @@ group :development, :test do
 end
 
 group :development do
+  gem "brakeman", "6.1.2"
+  gem "bullet"
   # To ensure code consistency [https://docs.rubocop.org]
   gem "rubocop", "1.56.2"
   gem "rubocop-factory_bot", "!= 2.26.0", require: false
@@ -118,8 +122,6 @@ group :development do
   gem "rubocop-rspec_rails", "!= 2.29.0", require: false
   # Use console on exceptions pages [https://github.com/rails/web-console]
   gem "web-console", "4.2.1"
-  gem "bullet"
-  gem "brakeman", "6.1.2"
 
   # Preview mail in the browser instead of sending.
   gem "letter_opener", "1.10.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 936d7982..b734d288 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -225,6 +225,10 @@ GEM
       activesupport (>= 6.1)
     hashery (2.1.2)
     hashie (5.0.0)
+    httparty (0.23.2)
+      csv
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
     i18n (1.14.5)
       concurrent-ruby (~> 1.0)
     importmap-rails (2.0.1)
@@ -454,6 +458,8 @@ GEM
       io-console (~> 0.5)
     request_store (1.7.0)
       rack (>= 1.4)
+    resend (0.26.0)
+      httparty (>= 0.21.0)
     responders (3.1.1)
       actionpack (>= 5.2)
       railties (>= 5.2)
@@ -645,6 +651,7 @@ DEPENDENCIES
   rails (= 7.1.3.4)
   redis (= 5.2.0)
   reek (= 6.3.0)
+  resend
   rspec-rails (= 6.0.3)
   rspec-sidekiq (= 4.0.2)
   rubocop (= 1.56.2)
diff --git a/app/controllers/api/v1/event_procedures_controller.rb b/app/controllers/api/v1/event_procedures_controller.rb
index a88806ef..644cbc8c 100644
--- a/app/controllers/api/v1/event_procedures_controller.rb
+++ b/app/controllers/api/v1/event_procedures_controller.rb
@@ -6,28 +6,28 @@ class EventProceduresController < ApiController
       after_action :verify_authorized, except: :index
       after_action :verify_policy_scoped, only: :index
 
-    def index
-      authorized_scope = policy_scope(EventProcedure)
-
-      listed_event_procedures = EventProcedures::List.result(
-        scope:  authorized_scope,
-        params: event_procedure_permitted_query_params
-      )
-
-      event_procedures              = listed_event_procedures.event_procedures
-      event_procedures_unpaginated  = listed_event_procedures.event_procedures_unpaginated
-
-      total_amount_cents = EventProcedures::TotalAmountCents.call(
-        event_procedures: event_procedures_unpaginated
-      )
-
-      render json: {
-        total:        total_amount_cents.total,
-        total_paid:   total_amount_cents.paid,
-        total_unpaid: total_amount_cents.unpaid,
-        event_procedures: serialized_event_procedures(event_procedures)
-      }, status: :ok
-    end
+      def index
+        authorized_scope = policy_scope(EventProcedure)
+
+        listed_event_procedures = EventProcedures::List.result(
+          scope: authorized_scope,
+          params: event_procedure_permitted_query_params
+        )
+
+        event_procedures = listed_event_procedures.event_procedures
+        event_procedures_unpaginated = listed_event_procedures.event_procedures_unpaginated
+
+        total_amount_cents = EventProcedures::TotalAmountCents.call(
+          event_procedures: event_procedures_unpaginated
+        )
+
+        render json: {
+          total: total_amount_cents.total,
+          total_paid: total_amount_cents.paid,
+          total_unpaid: total_amount_cents.unpaid,
+          event_procedures: serialized_event_procedures(event_procedures)
+        }, status: :ok
+      end
 
       def create
         authorize(EventProcedure)
diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index 5cc63a0c..c97d4595 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
 class ApplicationMailer < ActionMailer::Base
-  default from: "from@example.com"
   layout "mailer"
 end
diff --git a/config/environments/development.rb b/config/environments/development.rb
index e6aa2168..132f388c 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -66,10 +66,10 @@
 
   # The Bullet gem helps detect N+1 queries and other inefficiencies in ActiveRecord queries.
   config.after_initialize do
-    Bullet.enable        = true
-    Bullet.alert         = true
+    Bullet.enable = true
+    Bullet.alert = true
     Bullet.bullet_logger = true
-    Bullet.console       = true
+    Bullet.console = true
   end
 
   # Raises error for missing translations.
@@ -86,6 +86,8 @@
 
   config.action_mailer.default_url_options = { host: "localhost", port: 3000 }
 
+  # Use letter_opener to local development or resend to test real emails
   config.action_mailer.delivery_method = :letter_opener
+  # config.action_mailer.delivery_method = :resend
   config.action_mailer.perform_deliveries = true
 end
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 22eaf779..d6001e52 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -99,16 +99,5 @@
 
   config.action_mailer.default_url_options = { host: "api.meusprocedimentos.com.br", protocol: "https" }
 
-  config.action_mailer.delivery_method = :smtp
-  config.action_mailer.smtp_settings = {
-    address: "smtp.sendgrid.net",
-    port: 587,
-    domain: "meusprocedimentos.com.br",
-    user_name: Rails.application.credentials.dig(:smtp, :username),
-    password: Rails.application.credentials.dig(:smtp, :password),
-    authentication: "plain",
-    enable_starttls: true,
-    open_timeout: 5,
-    read_timeout: 5
-  }
+  config.action_mailer.delivery_method = :resend
 end
diff --git a/config/initializers/mailer.rb b/config/initializers/mailer.rb
new file mode 100644
index 00000000..c8b64044
--- /dev/null
+++ b/config/initializers/mailer.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+Resend.api_key = ENV.fetch("RESEND_API_KEY", nil)
diff --git a/config/initializers/rack_attack.rb b/config/initializers/rack_attack.rb
index 0aeb6e1f..2498c273 100644
--- a/config/initializers/rack_attack.rb
+++ b/config/initializers/rack_attack.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 class Rack::Attack
-
   ### Configure Cache ###
 
   # If you don't want to use Rails.cache (Rack::Attack's default), then
@@ -11,7 +10,7 @@ class Rack::Attack
   # safelisting). It must implement .increment and .write like
   # ActiveSupport::Cache::Store
 
-  Rack::Attack.cache.store = ActiveSupport::Cache::MemoryStore.new 
+  Rack::Attack.cache.store = ActiveSupport::Cache::MemoryStore.new
 
   ### Throttle Spammy Clients ###
 
@@ -26,7 +25,7 @@ class Rack::Attack
   # Throttle all requests by IP (60rpm)
   #
   # Key: "rack::attack:#{Time.now.to_i/:period}:req/ip:#{req.ip}"
-  throttle('req/ip', limit: 300, period: 5.minutes) do |req|
+  throttle("req/ip", limit: 300, period: 5.minutes) do |req|
     req.ip # unless req.path.start_with?('/assets')
   end
 
@@ -42,10 +41,8 @@ class Rack::Attack
   # Throttle POST requests to /login by IP address
   #
   # Key: "rack::attack:#{Time.now.to_i/:period}:logins/ip:#{req.ip}"
-  throttle('logins/ip', limit: 5, period: 20.seconds) do |req|
-    if req.path == '/login' && req.post?
-      req.ip
-    end
+  throttle("logins/ip", limit: 5, period: 20.seconds) do |req|
+    req.ip if req.path == "/login" && req.post?
   end
 
   # Throttle POST requests to /login by email param
@@ -56,11 +53,11 @@ class Rack::Attack
   # throttle logins for another user and force their login requests to be
   # denied, but that's not very common and shouldn't happen to you. (Knock
   # on wood!)
-  throttle('logins/email', limit: 5, period: 20.seconds) do |req|
-    if req.path == '/login' && req.post?
+  throttle("logins/email", limit: 5, period: 20.seconds) do |req|
+    if req.path == "/login" && req.post?
       # Normalize the email, using the same logic as your authentication process, to
       # protect against rate limit bypasses. Return the normalized email if present, nil otherwise.
-      req.params['email'].to_s.downcase.gsub(/\s+/, "").presence
+      req.params["email"].to_s.downcase.gsub(/\s+/, "").presence
     end
   end
 
@@ -78,4 +75,3 @@ class Rack::Attack
   #    ['']] # body
   # end
 end
-
diff --git a/spec/operations/event_procedures/list_spec.rb b/spec/operations/event_procedures/list_spec.rb
index 4baaa45d..2050528a 100644
--- a/spec/operations/event_procedures/list_spec.rb
+++ b/spec/operations/event_procedures/list_spec.rb
@@ -3,7 +3,6 @@
 require "rails_helper"
 
 RSpec.describe EventProcedures::List, type: :operation do
-
   describe ".result" do
     it "is successful" do
       result = described_class.result(scope: EventProcedure.all, params: {})
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 524c7586..f1573a41 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -75,7 +75,7 @@
   Rails.root.glob("spec/support/**/*.rb").each { |f| require f }
 
   # Clears Rack:Attack cache between specs
-  config.before(:each) do
+  config.before do
     Rack::Attack.cache.store.clear if Rack::Attack.cache.store.respond_to?(:clear)
   end
 end
diff --git a/spec/support/query_helper.rb b/spec/support/query_helper.rb
index 230b9e9b..7697ccd4 100644
--- a/spec/support/query_helper.rb
+++ b/spec/support/query_helper.rb
@@ -1,13 +1,13 @@
 # frozen_string_literal: true
 
 module QueryHelper
-  def count_queries(&block)
+  def count_queries(&)
     queries = []
-    callback = ->(_name, _start, _finish, _id, payload) do
-      queries << payload[:sql] unless payload[:name] =~ /SCHEMA|TRANSACTION/
+    callback = lambda do |_name, _start, _finish, _id, payload|
+      queries << payload[:sql] unless /SCHEMA|TRANSACTION/.match?(payload[:name])
     end
 
-    ActiveSupport::Notifications.subscribed(callback, "sql.active_record", &block)
+    ActiveSupport::Notifications.subscribed(callback, "sql.active_record", &)
     queries.count
   end
 end