It would be easier to add something like a `forbid` policy to DMARC IMO, since you'd want to set up DMARC to monitor spoof attempts anyway. A simple `p=forbid,

It would be easier to add something like a `forbid` policy to DMARC IMO, since you'd want to set up DMARC to monitor spoof attempts anyway. A simple `p=forbid,sp=forbid` (not real options) in DMARC would be ideal. forbid - all mail is forbidden regardless of DMARC alignment