diff --git a/.rubocop.yml b/.rubocop.yml
index b1c8b19..144320f 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -11,11 +11,5 @@ Style:
 Layout:
   Enabled: false
 
-Metrics/BlockLength:
-  Max: 50
-
-Metrics/MethodLength:
-  Max: 40
-
-Metrics/AbcSize:
-  Max: 50
+Metrics:
+  Enabled: false
diff --git a/app/helpers/messages_helper.rb b/app/helpers/messages_helper.rb
index 5981d9b..94ef84a 100644
--- a/app/helpers/messages_helper.rb
+++ b/app/helpers/messages_helper.rb
@@ -7,18 +7,18 @@ def without_list_prefix(subject)
   def search_snippet(body, keyword)
     snippet = ''
 
-      offset = 0
-      while (i = body.index(keyword, offset))
-        start = [i - MARGIN, offset].max
-          len = keyword.length + MARGIN
-          snippet += body[start, len]
-          offset = start + len
-      end
+    offset = 0
+    while (i = body.index(keyword, offset))
+      start = [i - MARGIN, offset].max
+      len = keyword.length + MARGIN
+      snippet += body[start, len]
+      offset = start + len
+    end
 
-      if snippet.empty?
-        return body[0, MARGIN * 2]
-      else
-        snippet
-      end
+    if snippet.empty?
+      return body[0, MARGIN * 2]
+    else
+      snippet
+    end
   end
 end
diff --git a/app/models/list.rb b/app/models/list.rb
index 641da36..d87c3cb 100644
--- a/app/models/list.rb
+++ b/app/models/list.rb
@@ -1,16 +1,16 @@
 class List
   def initialize(name, id)
     @name = name
-      @id = id
+    @id = id
   end
   attr_reader :name, :id
 
-    # Ordered by the established dates. ruby-list was started in 1995.
+  # Ordered by the established dates. ruby-list was started in 1995.
   LISTS = [
-      List.new('ruby-list', 1),
-      List.new('ruby-dev', 2),
-      List.new('ruby-core', 3),
-      List.new('ruby-talk', 4),
+    List.new('ruby-list', 1),
+    List.new('ruby-dev', 2),
+    List.new('ruby-core', 3),
+    List.new('ruby-talk', 4),
   ]
 
   def self.find_by_name(name)
diff --git a/app/models/message.rb b/app/models/message.rb
index 45390d1..1f5151b 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -4,28 +4,29 @@
 require 'kconv'
 
 class Message < ApplicationRecord
-    # Not really sure we will utlize this configuration,
-    # but I don't want to make this column.
-    # https://blade.ruby-lang.org/ruby-talk/1 is JST.
-    # https://blade.ruby-lang.org/ruby-talk/410000 is not.
+  # Not really sure we will utlize this configuration,
+  # but I don't want to make this column.
+  # https://blade.ruby-lang.org/ruby-talk/1 is JST.
+  # https://blade.ruby-lang.org/ruby-talk/410000 is not.
   self.skip_time_zone_conversion_for_attributes = [:published_at]
 
-  def self.from_s3(list_name, list_seq, s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))
-    obj = s3_client.get_object(bucket: BLADE_BUCKET_NAME, key: "#{list_name}/#{list_seq}")
+  class << self
+    def from_s3(list_name, list_seq, s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))
+      obj = s3_client.get_object(bucket: BLADE_BUCKET_NAME, key: "#{list_name}/#{list_seq}")
 
       m = self.from_string(obj.body.read)
       m.list_id = List.find_by_name(list_name).id
       m.list_seq = list_seq
       m
-  end
+    end
 
-  def self.from_string(str)
+    def from_string(str)
       # There are a few hacks to import messages from blade.ruby-lang.org's
       # S3 bucket.
 
       # Need to call String#b. There are messages that have headers in non-UTF8,
       # but the body is in UTF-8, such as ruby-list:2882.
-    headers_str, body = str.b.split(/\n\n/, 2)
+      headers_str, body = str.b.split(/\n\n/, 2)
 
       # ruby-list:2840 doesn't have a proper From header.
       headers_str = Kconv.toutf8(headers_str).gsub(/\r\n/, '')
@@ -37,21 +38,22 @@ def self.from_string(str)
       published_at = DateTime.strptime(headers['Date'], '%Y-%m-%dT%H:%M:%S%:z')
 
       self.new(
-          body: Kconv.toutf8(body),
-          subject: headers['Subject'],
-          from: headers['From'],
-          published_at: published_at,
+        body: Kconv.toutf8(body),
+        subject: headers['Subject'],
+        from: headers['From'],
+        published_at: published_at,
       )
+    end
   end
 
   def reload_from_s3(s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))
     m = Message.from_s3(List.find_by_id(self.list_id).name, self.list_seq, s3_client)
 
-      self.body = m.body
-      self.subject = m.subject
-      self.from = from
-      self.published_at = m.published_at
+    self.body = m.body
+    self.subject = m.subject
+    self.from = from
+    self.published_at = m.published_at
 
-      m
+    m
   end
 end
diff --git a/import.rb b/import.rb
index 7b151a5..71e4d92 100644
--- a/import.rb
+++ b/import.rb
@@ -3,21 +3,23 @@
 params = {}
 OptionParser.new do |opts|
   opts.on('--list LIST')
-    opts.on('--from FROM', Integer)
-    opts.on('--to TO', Integer)
+  opts.on('--from FROM', Integer)
+  opts.on('--to TO', Integer)
 end.parse!(into: params)
 
 list = params[:list]
 
-(params[:from]..params[:to]).each do |seq|
-  begin
-    message = Message.from_s3(list, seq)
-    message.save
-rescue ActiveRecord::RecordNotUnique
-  STDERR.puts("#{list}:#{seq} already exists in Postgres")
-rescue Aws::S3::Errors::NoSuchKey
-  STDERR.puts("#{list}:#{seq} doesn't exist in S3")
-rescue StandardError => e
-  STDERR.puts("failed to import #{list}:#{seq}: #{e}")
+Message.transaction do
+  (params[:from]..params[:to]).each do |seq|
+    begin
+      message = Message.from_s3(list, seq)
+      message.save!
+    rescue ActiveRecord::RecordNotUnique
+      STDERR.puts("#{list}:#{seq} already exists in Postgres")
+    rescue Aws::S3::Errors::NoSuchKey
+      STDERR.puts("#{list}:#{seq} doesn't exist in S3")
+    rescue StandardError => e
+      STDERR.puts("failed to import #{list}:#{seq}: #{e}")
+    end
   end
 end