They need to do a better job of managing their shared IP pool. As it is, they are offering paid plans that are unsuitable for many common use cases. Really, unless you have control of all possible receiving domains (e.g you're using it for an internal app), you're rolling the dice.

Else, at a minimum, they should disclose deliverability metrics on their various plans so customers can make informed choices. As it is, their marketing is deliberately misleading.

Thanks for the feedback on Postmark. I'll have another look at them.

EDIT: Just glanced at Postmark and they're already looking much stronger than SendGrid, and with much better pricing. The "deliverability without a dedicated IP" language seems to be directly aimed at providers like SendGrid. Are they able to live up to that promise?

Also like their policy around content retention.

Will be exploring switching costs.