wttw / aboutmyemail

Content for the aboutmy.email website
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SMTPUTF8 issue 4: use of e.g. 8859-1 in header fields #8

Open arnt opened 9 months ago

arnt commented 9 months ago

Hi,

it's a strange sight, but I've actually seen software that sends unencoded legal UTF8 in the address fields and unencoded justsend8 8859-1 in the subject. (The reason: overlooked legacy code.)

It would be great if aboutmy.email could detect any byte sequence in the header that isn't valid UTF8. All-ASCII header fields are of course valid UTF8, as are =?...?= sequences. What I've seen is strictly byte values >127.

I have no reason to believe that mixing encodings in this way has a significant impact on deliverability so I don't know that this is appropriate for aboutmy.email, I just think it's kind of smelly.