Do not encode message/rfc822 attachments into base64
Do not encode message/rfc822 attachments into base64

If there is a message/rfc822 attachment, which is not properly
saved as an embedded message object on the server (which some
older evolution-mapi could do), then these might not be encoded
in base64, rather keep them inline un-encoded.

GNOME/evolution-mapi,GNOME/evolution-mapi