diff --git a/action.py b/action.py
index 93ff02d..b2d0686 100644
--- a/action.py
+++ b/action.py
@@ -8,8 +8,7 @@ from trytond import backend
 __all__ = ['ActionReport', 'ActionWizard']
 
 
-class ActionReport:
-    __metaclass__ = PoolMeta
+class ActionReport(metaclass=PoolMeta):
     __name__ = 'ir.action.report'
     email_filename = fields.Char('Email File Name', translate=True,
         help='File name e-mail attachment without extension. '
@@ -28,7 +27,6 @@ class ActionReport:
         super(ActionReport, cls).__register__(module_name)
 
 
-class ActionWizard:
-    __metaclass__ = PoolMeta
+class ActionWizard(metaclass=PoolMeta):
     __name__ = 'ir.action.wizard'
     template = fields.One2Many("electronic.mail.template", 'wizard', 'Template')
diff --git a/activity.py b/activity.py
index 5858a56..0d0ef4c 100644
--- a/activity.py
+++ b/activity.py
@@ -7,8 +7,7 @@ from trytond import backend
 __all__ = ['Activity']
 
 
-class Activity:
-    __metaclass__ = PoolMeta
+class Activity(metaclass=PoolMeta):
     __name__ = "activity.activity"
 
     @classmethod
diff --git a/setup.py b/setup.py
index f5a642c..18902a9 100644
--- a/setup.py
+++ b/setup.py
@@ -7,10 +7,7 @@ from setuptools import setup
 import re
 import os
 import io
-try:
-    from configparser import ConfigParser
-except ImportError:
-    from ConfigParser import ConfigParser
+from configparser import ConfigParser
 
 MODULE = 'electronic_mail'
 PREFIX = 'trytonspain'
diff --git a/template.py b/template.py
index 1651919..b022e4e 100644
--- a/template.py
+++ b/template.py
@@ -13,11 +13,12 @@ from trytond.sendmail import SMTPDataManager, sendmail_transactional, sendmail
 from genshi.template import TextTemplate
 from jinja2 import Template as Jinja2Template
 from emailvalid import check_email
-from email import Encoders, charset
+from email import charset
 from email.header import decode_header, Header
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 from email.mime.base import MIMEBase
+from email.encoders import encode_base64
 from email.utils import formatdate, make_msgid
 
 __all__ = ['Template', 'TemplateReport', 'SendTemplateStart', 'SendTemplate']
@@ -130,7 +131,7 @@ class Template(ModelSQL, ModelView):
         '''Evaluate the pythonic expression and return its value
         '''
         if expression is None:
-            return u''
+            return ''
 
         assert record is not None, 'Record is undefined'
         template_context = cls.template_context(record)
@@ -143,7 +144,7 @@ class Template(ModelSQL, ModelView):
         :param record: Browse record
         '''
         if not expression:
-            return u''
+            return ''
 
         template = TextTemplate(expression)
         template_context = cls.template_context(record)
@@ -156,7 +157,7 @@ class Template(ModelSQL, ModelView):
         :param record: Browse record
         '''
         if not expression:
-            return u''
+            return ''
 
         template = Jinja2Template(expression)
         template_context = cls.template_context(record)
@@ -294,7 +295,7 @@ class Template(ModelSQL, ModelView):
         vals = []
         for record in records:
             val = {}
-            for k, v in data.iteritems():
+            for k, v in data.items():
                 value = cls.eval(v, record, engine)
                 if k in ['from_', 'sender', 'to', 'cc', 'bcc']:
                     value = value.replace(' ', '').replace(',', ';')
@@ -408,7 +409,7 @@ class Template(ModelSQL, ModelView):
 
                     attachment = MIMEBase(maintype, subtype)
                     attachment.set_payload(data)
-                    Encoders.encode_base64(attachment)
+                    encode_base64(attachment)
                     attachment.add_header(
                         'Content-Disposition', 'attachment', filename=filename)
                     message.attach(attachment)
@@ -494,7 +495,7 @@ class SendTemplate(Wizard):
         default = {}
         default['template'] = template.id
         default['total'] = total
-        for k, v in template.pre_render(records)[0].iteritems():
+        for k, v in template.pre_render(records)[0].items():
             default[k] = v
         return default
 
diff --git a/tools.py b/tools.py
deleted file mode 100644
index e69de29..0000000
diff --git a/trigger.py b/trigger.py
index 53abb36..dfb5fac 100644
--- a/trigger.py
+++ b/trigger.py
@@ -8,8 +8,7 @@ from trytond.pool import Pool, PoolMeta
 __all__ = ['Trigger']
 
 
-class Trigger:
-    __metaclass__ = PoolMeta
+class Trigger(metaclass=PoolMeta):
     __name__ = 'ir.trigger'
     email_template = fields.Many2One('electronic.mail.template', 'Template')
 
diff --git a/user.py b/user.py
index 2dc77dd..654734d 100644
--- a/user.py
+++ b/user.py
@@ -7,8 +7,7 @@ from trytond.model import fields
 __all__ = ['User']
 
 
-class User:
-    __metaclass__ = PoolMeta
+class User(metaclass=PoolMeta):
     __name__ = "res.user"
     signature_html = fields.Text('Signature HTML')