No dmarc policy (#263)
No dmarc policy (#263)

* Update data_post_headers documentation
We cannot reject at this stage, which is only there to alter headers.
Fix #258

* DMARC plugin: reject in data_post
Followup of #258: we cannot reject a connection during data_post_headers. So add a new hook in data_post to do the real rejection

* Support spf rejects when no DMARC policy is published
When using DMARC, you have to run sender_permitted_from first, and without rejecting anything. If a DMARC policy is published, then fine, the dmarc plugin will handle this. But if there's no DMARC policy at all, then we can decide solely on SPF to reject on not. This decision must be taken after dmarc runs, so, add a hook into post_data (dmarc is evaluated in post_data_headers). A new no_dmarc_policy argument is available and you can decide the level at wich you want to reject on SPF failures

* Typo

priyadi/qpsmtpd,smtpd/qpsmtpd,priyadi/qpsmtpd,smtpd/qpsmtpd,salvis/qpsmtpd,salvis/qpsmtpd,priyadi/qpsmtpd