diff --git a/activity.py b/activity.py
index a88919f..52dd2ee 100644
--- a/activity.py
+++ b/activity.py
@@ -5,7 +5,7 @@ from trytond.model import fields, ModelView
 from trytond.transaction import Transaction
 from trytond.wizard import Wizard, StateAction
 from email.utils import parseaddr, formataddr, formatdate, make_msgid
-from email import Encoders
+from email import encoders
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 from email.mime.base import MIMEBase
@@ -24,9 +24,8 @@ except ImportError:
 __all__ = ['Activity', 'ActivityReplyMail']
 
 
-class Activity:
+class Activity(metaclass=PoolMeta):
     __name__ = 'activity.activity'
-    __metaclass__ = PoolMeta
 
     mail = fields.Many2One('electronic.mail', "Related Mail", readonly=True,
             ondelete='CASCADE')
@@ -222,7 +221,7 @@ class Activity:
                     ).split('/', 1)
                 attachment = MIMEBase(maintype, subtype)
                 attachment.set_payload(data)
-                Encoders.encode_base64(attachment)
+                encoders.encode_base64(attachment)
                 attachment.add_header(
                     'Content-Disposition', 'attachment', filename=filename)
                 attachment.add_header(
@@ -274,7 +273,7 @@ class Activity:
 
         values = []
         attachs = {}
-        for server_id, mails in received_mails.iteritems():
+        for server_id, mails in list(received_mails.items()):
             servers = IMAPServer.browse([server_id])
             server = servers and servers[0] or None
             for mail in mails:
@@ -411,7 +410,7 @@ class Activity:
                                 })
                     try:
                         Attachment.create(values)
-                    except Exception, e:
+                    except Exception as e:
                         logging.getLogger('Activity Mail').info(
                             'The mail (%s) has attachments but they are not '
                             'possible to attach to the activity (%s).\n\n%s' %
@@ -419,10 +418,9 @@ class Activity:
         return mails
 
 
-class ActivityReplyMail(Wizard):
+class ActivityReplyMail(Wizard, metaclass=PoolMeta):
     'Activity Reply Mail'
     __name__ = 'activity.activity.replymail'
-    __metaclass__ = PoolMeta
     start_state = 'open_'
     open_ = StateAction('activity.act_activity_activity')
 
diff --git a/imap.py b/imap.py
index 088e250..f583096 100644
--- a/imap.py
+++ b/imap.py
@@ -4,10 +4,9 @@ from trytond.pool import Pool, PoolMeta
 from trytond.model import fields
 
 __all__ = ['IMAPServer']
-__metaclass__ = PoolMeta
 
 
-class IMAPServer:
+class IMAPServer(metaclass=PoolMeta):
     __name__ = 'imap.server'
 
     employee = fields.Many2One('company.employee', 'Default Employee')
diff --git a/setup.py b/setup.py
index 8ef3ecc..c9743c3 100644
--- a/setup.py
+++ b/setup.py
@@ -4,7 +4,7 @@
 from setuptools import setup
 import re
 import os
-import ConfigParser
+import configparser
 
 MODULE = 'electronic_mail_activity'
 PREFIX = 'nantic'
@@ -24,7 +24,7 @@ def get_require_version(name):
         major_version, minor_version + 1)
     return require
 
-config = ConfigParser.ConfigParser()
+config = configparser.ConfigParser()
 config.readfp(open('tryton.cfg'))
 info = dict(config.items('tryton'))
 for key in ('depends', 'extras_depend', 'xml'):
diff --git a/user.py b/user.py
index 811733e..b0a4553 100644
--- a/user.py
+++ b/user.py
@@ -4,10 +4,9 @@ from trytond.pool import PoolMeta
 from trytond.model import fields
 
 __all__ = ['User']
-__metaclass__ = PoolMeta
 
 
-class User:
+class User(metaclass=PoolMeta):
     __name__ = "res.user"
 
     smtp_server = fields.Many2One('smtp.server', 'SMTP Server',