Klaviyo runs the email flows for every e-commerce store owner we talked to, while Postmark has declined after being acquired.
Only use Postmark if you have a specific need for its transactional email past, otherwise stick with Klaviyo for your store.
Klaviyo blows Postmark out of the water for email marketing if you're running an e-commerce store. Klaviyo is the go-to for building out sales sequences, upsells, and abandoned cart flows, with templates proven to work across the e-commerce space. Everyone in e-commerce seems to use it, and it's basically the default tech stack for this kind of email work.
Postmark is focused on transactional emails, like password resets, and even there, it's lost its edge after being acquired. It's just not built for the marketing flows, automation, or personalization that Klaviyo nails for e-commerce.
If you care about effective email marketing and automation for e-commerce, Klaviyo is the clear pick. Postmark doesn't even play in the same league for this use case.
