attempt to encode encrypted messages the same as unencrypted input

.gitignore

@@ -1,2 +1,4 @@
 venv/
 .idea/
+testing.py
+

gpgmymail

@@ -40,6 +40,13 @@ import gnupg
 
 # constants
 DEFAULT_ENCODING='utf-8'  # default is latin-1 which fails w some unicode chars
+CONTENT-TRANSFER-ENCODING_TO_ENCODER_DICT = {
+    "7bit": email.encoders.encode_7or8bit,
+    "8bit": email.encoders.encode_7or8bit,
+    "base64": email.encoders.encode_base64,
+    "quoted-printable": email.encoders.encode_quopri
+}
+DEFAULT_ENCODER = email.encoders.encode_7or8bit
 
 def is_message_encrypted(message: email.message.Message) -> bool:
     """Determines whether or not an email message is encrypted.
@@ -49,6 +56,24 @@ def is_message_encrypted(message: email.message.Message) -> bool:
 
     return message.get_content_subtype() == "encrypted"
 
+def get_encoder_from_msg(msg: email.message.Message) -> function:
+    """
+    Return a suitable encoder function from email.encoders based on an input
+    message. If the input message has no Content-Transfer-Encoding header,
+    or there is no encoder function corresponding to the CTE header, a default
+    encoder will be returned.
+
+    :param msg: an unencrypted email Message
+    :return: function from email.encoders, see
+             https://docs.python.org/3/library/email.encoders.html
+    """
+    cte = msg.get("Content-Transfer-Encoding")
+    if cte:
+        encoder = CONTENT-TRANSFER-ENCODING_TO_ENCODER_DICT.get(cte)
+    else:
+        return DEFAULT_ENCODER
+    return encoder if encoder else DEFAULT_ENCODER
+
 def encrypt(
         message: email.message.Message,
         recipients: typing.List[str],
@@ -82,13 +107,13 @@ def encrypt(
     enc = email.mime.application.MIMEApplication(
         _data=str(encrypted_content).encode(),
         _subtype="octet-stream",
-        _encoder=email.encoders.encode_7or8bit
+        _encoder=get_encoder_from_msg(message)
     )
 
     control = email.mime.application.MIMEApplication(
         _data=b'Version: 1\n',
         _subtype='pgp-encrypted; name="msg.asc"',
-        _encoder=email.encoders.encode_7or8bit
+        _encoder=get_encoder_from_msg(message)
     )
     control['Content-Disposition'] = 'inline; filename="msg.asc"'