Another 2 to 3 mail encoding problem

[Chris Green]

Terry Reedy <tjreedy at udel.edu> wrote:
> On 8/26/2020 11:10 AM, Chris Green wrote:
> 
> > I have a simple[ish] local mbox mail delivery module as follows:-
> ...
> > It has run faultlessly for many years under Python 2.  I've now
> > changed the calling program to Python 3 and while it handles most
> > E-Mail OK I have just got the following error:-
> > 
> >      Traceback (most recent call last):
> >        File "/home/chris/.mutt/bin/filter.py", line 102, in <module>
> >          mailLib.deliverMboxMsg(dest, msg, log)
> ...
> >        File "/usr/lib/python3.8/email/generator.py", line 406, in write
> >          self._fp.write(s.encode('ascii', 'surrogateescape'))
> > UnicodeEncodeError: 'ascii' codec can't encode character '\ufeff' in 
> position 4: ordinal not in range(128) 
> 
> '\ufeff' is the Unicode byte-order mark.  It should not be present in an 
> ascii-only 3.x string and would not normally be present in general 
> unicode except in messages like this that talk about it.  Read about it, 
> for instance, at
> https://en.wikipedia.org/wiki/Byte_order_mark
> 
> I would catch the error and print part or all of string s to see what is 
> going on with this particular message.  Does it have other non-ascii chars?
> 
I can provoke the error simply by sending myself an E-Mail with
accented characters in it.  I'm pretty sure my Linux system is set up
correctly for UTF8 characters, I certainly seem to be able to send and
receive these to others and I even get to see messages in other
scripts such as arabic, chinese, etc.

The code above works perfectly in Python 2 delivering messages with
accented (and other extended) characters with no problems at all.
Sending myself E-Mails with accented characters works OK with the code
running under Python 2.

While an E-Mail body possibly *shouldn't* have non-ASCII characters in
it one must be able to handle them without errors.  In fact haven't
the RFCs changed such that the message body should be 8-bit clean?
Anyway I think the Python 3 mail handling libraries need to be able to
pass extended characters through without errors.

-- 
Chris Green
·