Flowmails vs Postmark
Transactional email with strong deliverability and a separate broadcast product. This page is a side-by-side on the parts that matter when you're considering a switch — data residency, pricing, and the parts of each stack that show up in a real migration.
At a glance
Three sentence compare.
Pricing shape
Postmark's free tier is 100 emails/month; paid starts at $15 / month for 10,000 emails, with separate pricing for broadcast. Flowmails Base is $0; Pro is $9.9 / month and Enterprise is $39.9 / month.
Setup shape
Postmark is hosted — sign up, verify sender signature, call the API. Flowmails connects your domain provider over OAuth and runs the shared mail worker for every tenant.
Best fit
Postmark: teams that want a hosted ESP with both transactional and broadcast under the same account. Flowmails: teams that don't need broadcast or want it handled by a separate tool.
Feature matrix
Postmark vs Flowmails, line by line.
| Feature | Postmark | Flowmails |
|---|---|---|
| Data residency | Postmark multi-tenant (ActiveCampaign) | Flowmails' own storage, scoped by domain id |
| Inbound parse | Yes | Yes |
| Broadcast / newsletters | Yes (separate product) | No (transactional only) |
| Templates | Yes (Postmark template engine) | Plain HTML / text in your code or dashboard |
| SMTP relay | Yes | No |
| Per-email pricing | Yes | No |
Integration parity
SDK and runtime compatibility.
Postmark exposes an HTTP API and an SMTP relay. Flowmails is REST-only. SDK-wise, the surface areas are similar (send / receive / templates / stats).
Migrating
How to switch from Postmark to Flowmails.
Confirm you only need transactional email
If your team uses Postmark's broadcast product for newsletters, keep it — Flowmails doesn't replace it. The migration only covers the transactional surface.
Connect the domain's provider
Same prerequisite: the zone must be on a supported routing provider. Flowmails provisions Email Routing on the zone and an outbound provider per domain.
Port templates and SDK calls
Postmark templates use the `{{variable}}` Mustache-style syntax — port them to either plain HTML in your Worker or a templating layer of your choice. SDK calls swap to Flowmails SDK calls.
Other comparisons