'man procmailex' tells you that a recipe starting with egreps the message body for a string:
Code:
:0 Bb
* ^.*verified.ok
and 'man formail' says to use "-a field name" to add a header field to a message so yes, this seems possible.
Of course it would be
way easier to modify the backup script to provide a useful subject line or add a header based on the processes exit status...