helper: replace email_as_* with email builtins

Python 3.3 added a new feature to the email module, policies
(https://docs.python.org/3.5/library/email.policy.html). Policy objects
allow precise control over how numerous features work when converting to
and from str or bytes. With the `email.policy.SMTP` the behavior of
email_as_bytes and email_as_string can be achieved using the builtin
`.as_string()` and `.as_bytes()` methods, without custom code or the
need to test it. Additionally these methods handle corner cases that we
don't currently handle, such as multi-part messages with different
encodings.

Fixes #1257

1 files changed, 3 insertions, 2 deletions

diff --git a/alot/commands/thread.py b/alot/commands/thread.py
index 801ce2f0..6513872c 100644
--- a/alot/commands/thread.py
+++ b/alot/commands/thread.py
@@ -9,6 +9,8 @@ import os
 import re
 import subprocess
 import tempfile
+import email
+import email.policy
 from email.utils import getaddresses, parseaddr, formataddr
 from email.message import Message
 
@@ -34,7 +36,6 @@ from ..db.errors import DatabaseROError
 from ..settings.const import settings
 from ..helper import parse_mailcap_nametemplate
 from ..helper import split_commandstring
-from ..helper import email_as_string
 from ..utils import argparse as cargparse
 from ..widgets.globals import AttachmentWidget
 
@@ -382,7 +383,7 @@ class ForwardCommand(Command):
             original_mail = Message()
             original_mail.set_type('message/rfc822')
             original_mail['Content-Disposition'] = 'attachment'
-            original_mail.set_payload(email_as_string(mail))
+            original_mail.set_payload(mail.as_string(policy=email.policy.SMTP))
             envelope.attach(Attachment(original_mail))
 
         # copy subject