opendmarc-reports: can't set "email" inside the report separatly

[andreasschulze]

inside the reports generated by opendmarc-reports there is a block report_metadatacontaining a field email

I did not found something about the meaning of that field in RFC 7489
My personal archive of received reports show most of the time report_metadata.email = rfc5321.mailfrom = rfc5322.from,
but some sender used a different address then rfc5321.mailfrom and rfc5322.from.

Some clarification I found in an Internet draft: https://datatracker.ietf.org/doc/draft-ietf-dmarc-aggregate-reporting/
https://www.ietf.org/archive/id/draft-ietf-dmarc-aggregate-reporting-32.html#xml-report-metadata say:

email: Contact to use when contacting the Reporting Organization.

There is no formal requirement, report_metadata.email must match rfc5321.mailfrom or rfc5322.from and I suggest to implement a possibility to specify an address similar to the way, the report_metadata.org_name could be specified.

I'll provide a patch / merge request some time in the future