Hi,

I have reviewed this document as part of the security directorate's
ongoing effort to review all IETF documents being processed by the
IESG.  These comments were written primarily for the benefit of the
security area directors.  Document editors and WG chairs should treat
these comments just like any other last call comments.



Overall, the proposal to insert a MT-PRIORITY header appears reasonable. 


I don't think that it opens any security threats that are not noted in the 


document.






I am concerned that this feature can disrupt the DKIM protection as noted 


in section 11.1.  I see the problem here and I can't offer any suggestions 


to fix that.  I think that the authors have done well to document this.




Thanks,
Chris