On Oct 08, 2015, at 08:44 PM, Mauro S. M. Rodrigues wrote:

>Python 3.5.0+ (3.5:1e99ba6b7c98, Oct  8 2015, 17:12:06) 
>[GCC 4.8.4] on linux
>Type "help", "copyright", "credits" or "license" for more information.
>>>> import smtpd
>>>> smtpd.SMTPServer(("127.0.0.1", 0), ('b',0),enable_SMTPUTF8=True,decode_data=True)
>Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
>  File "/home/maurosr/dev/cpython/Lib/smtpd.py", line 645, in __init__
>    raise ValueError("The decode_data and enable_SMTPUTF8"
>ValueError: The decode_data and enable_SMTPUTF8 parameters cannot be set to True at the same time.

That's testing the SMTPServer.__init__() which looks fine.  It's the
SMTPChannel.__init__() that's broken.