[cj]

Google themselves recommends sending different types of emails from different subdomains of the primary domain to help Google differentiate between transactional, marketing, newsletters, outbound, etc

Any half decent marketer will 100% use a different domain for outbound sales (or any use case where spam rate might be abnormally high).

[xarope]

absolutely. You should/must separate transactional emails (account creations, password resets etc) from EDM (marketing emails).

[xoneill]

Thank! Will look into this and reconsider.