transactional mail Summary: See T571. SES refuses to deliver mail with this header and there are various reports of other issues on the internet so I'm defaulting it to off. Test Plan: Set config to true, tried to send mail, SES rejected it because of "Precedence: bulk" header. Reviewers: bmaurer, ola, jungejason, nh, aran Reviewed By: aran CC: aran, epriestley, bmaurer Differential Revision: 1032