Why are weekly RC bug reports 'unknown-8bit'?

[Jörg Sommer <joerg@alea.gnuu.de>]

Hi,

the weekly send reports about release critical bugs to
debian-devel-announce have the Content-Type “unknown-8bit” set. Why this?
What is unknown for the encoding of the reports?

And why is the sender of the reports not a valid address?

  bugscan@bugs.debian.org
    (generated from bugscan@debian.org)
    SMTP error from remote mailer after RCPT TO:<bugscan@bugs.debian.org>:
    host bugs.debian.org [140.211.166.43]: 550 unknown user

Bye, Jörg.
-- 
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weinen, als in der Straßenbahn.
	       	   	       			(Marcel Reich‐Ranicki)