[SOLVED] Sendmail with OpenDMARC

bitfuzzy · 12-08-2018, 06:50 AM

Environment:
Slackware 14.1 with Sendmail
DNS has been setup with DKIM, SPF, DMARC, and adsp for months

I've installed OpenDMARC in the hopes to drop spoofed emails.
Since I'm still testing, reporting has not been configured yet.

OpenDMARC is configured with:

Code:

SPFSelfValidate true
HistoryFile /var/run/opdndmarc/opendmarc.dat
IgnoreAuthenticated clients true
IgnoreHosts /usr/local/etc/opendmarc/ignore.hosts
RejectFailures false

The OpenDMARC dat file indicates that it's identifying message properties correctly. However all messages are being delivered

The expected behavior was for the sending domains handling disposition (Reject/Quarantine/None) for failed alignment to be followed if it exists

For example:

My adsp record indicates that messages that fail alignment should be rejected

If I send myself a message from a hosted domain, its detected as being local and is delivered. Which is correct

When I use a external server and forge a message from myself to myself, It fails alignment (correct) and is delivered (incorrect)

What am I missing to get message handling according to disposition working??

bitfuzzy · 12-08-2018, 10:59 AM

After finally finding a little information on the process, it appears that setting

Code:

RejectFailures false

to

Code:

RejectFailures true

might actually answer the question

The only thing I hate more than poorly documented software, is poorly worded comments regarding functions :\

I'm testing now, but given it's Saturday mail flow is low so it'll take a while until I get enough traffic to verify variances

bitfuzzy · 12-09-2018, 07:54 AM

Despite the wording within the config files comments, un-commenting

Code:

RejectFailures

and setting it to true will cause messages to be Rejected or Quarantined based on the Domains DMARC disposition setting "IF" present. If the Disposition is "None" then the message gets delivered