I've just had a bounce from the MTA running on mx1.solardns.com, which
advertises itself as Exim 20220503.1020
The bounce was:
550 Messages should have one or no Cc headers, not 2
I'd never seen this before, so I went off to check RFC5822, and I see
that in the 5822 version, only one of the To:, CC: or BCC: headers is
allowed to be generated.
However, the RFC says that implementations MUST accept the (now)
obsolete syntax, and SHOULD treat multiple destination address headers
in the obvious way.
Coming to the point: is the bounce message coming from some (hopefully
experimental) part of Exim, or must it have been maliciously
hand-crafted in a config file by the solardns administrators?
