Disclosure: I used to work at Postmark. ISPs are way more interested in maintaining relationships with ESPs that keep junk from getting to them in the first pl

Disclosure: I used to work at Postmark. ISPs are way more interested in maintaining relationships with ESPs that keep junk from getting to them in the first place than the ones that "quickly fix once the damage is done". It's one case where "asking for forgiveness" isn't preferred over the more careful approach. SES is more like outsourcing sendmail on your own server so you don't carry the burden of maintaining/securing it, except that you don't have control over it when something goes wrong and you have the same lack of customer support if you don't know how to fix it. If you value your messages getting to the inbox, it's the least desirable option. For sending low-value emails, though, go nuts!