This mail is utterly broken, it's nearly unbelievable. How did you end up with a mail like that? Could you elaborate the workflow? The decoding won't be fixed, but it encoding ops will if that's SOGo that has generated all that junk.

outlook is able to parse it, and thunerbird too

the mail was sent by a weather-station-service and forwarded via the opengroupware.org, and its not the only mail which is broken. i can provide you with more expamples of real-world-mails.. ulgy ones.

please add the original mail and a forwarded copy of it

and just to make sure, it was forwarded using OGo, not SOGo right?

Bug downgraded as no feedback was provided in months.

No feedback for more than a year. Bug closed.