>> we can relax the requirement that email headers be strictly ASCII. I'll
>> push a fix and let you know.
>
> Great, thanks.

Let me know if the fix works for you.

> In terms of where this message came from, I'm using getmail [1] to
> recieve the messages, then using the external MTA delivery config to
> pass the message off to a Guile script. I was processing the messages as
> strings, but I'm switching to using bytevectors.

Ok.

> I believe this issue happens with strings and bytevectors.

Yes, you are right. The issue of strings and bytevectors is
orthogonal. An email is a bag of bytes (not a bag of characters) -- a
binary file that needs to be parsed by guile-email.

> I've checked my mailserver, and the file corresponding to the sample
> email provided doesn't look to have a pure ASCII from header (in the
> terminal, I see a ? instead of è, so I'm not sure what's going on
> there).

Not sure which line you are referring to, but in Icecat, as far as I can
tell, I see all the 'è's correctly. Perhaps it's a decoding issue with
whichever viewer you are using.