SendGrid vs Postmark: price, deliverability tooling and migration

Price at the volumes each vendor publishes

SendGrid's plan selector stops at 50,000, 100,000, 300,000 and larger volumes, while Postmark's slider stops at 10,000, 50,000, 125,000 and 300,000. Only some stops line up, so the table leaves a dash where one vendor shows no price. Readouts are from each pricing page on 7 October 2026.

Postmark lists extra emails beyond the included volume at $1.80, $1.30 and $1.20 per 1,000 on Basic, Pro and Platform. Between the stops above, read the number off Postmark's slider rather than extrapolating from the overage rate. The practical reading is that SendGrid undercuts Postmark by a wide margin at 50,000 emails, which is where many growing apps sit, and that the advantage mostly disappears by 300,000.

What you get on each plan

Postmark's three paid plans share one price curve and differ in limits. Basic includes 45-day data retention and 5 custom sending domains; Pro adds retention customizable up to 365 days, 10 custom sending domains and inbound email processing; Platform lifts the domain limit to unlimited, which is aimed at agencies. All paid plans allow unlimited emails a day. SendGrid's Email API splits into Essentials, Pro with dedicated IPs included, and Premier at custom pricing.

Postmark's page also advertises "industry-leading deliverability rates & speed". That is the vendor's own claim, and this page has not measured it. What you can check is how each plan separates your traffic. Postmark's Message Streams keep transactional and broadcast email on separate streams, so a marketing send with a complaint spike does not share a stream with password resets.

Webhook security: signed or not

SendGrid's Event Webhook reports processed, delivered, deferred, bounce and dropped events and can be secured with its Signed Event Webhook, OAuth 2.0 or both (SendGrid event docs). Postmark's documentation says plainly that it does not currently support HMAC webhook signature verification. It recommends HTTP Basic Authentication combined with allowlisting its IP ranges, and it retries failed deliveries but not most 4xx responses (Postmark webhook docs). Write handlers that check each MessageID before acting so a retry cannot process the same event twice.

Dedicated IPs and add-ons

• SendGrid: Pro and Premier plans include dedicated IPs, with more available to purchase.
• Postmark: dedicated IPs start at $50 a month per IP, are limited to customers sending 300,000 emails a month or more, and require a Pro plan or higher. DMARC monitoring starts at $14 a month per domain, and custom activity retention starts at $5 a month.

Here is the same 300,000 emails a month with one dedicated IP on each side:

Which to choose

• Choose SendGrid if you send around 50,000 emails a month and cost matters most, need signed webhooks for a security review, or want one vendor for transactional and campaign email.
• Choose Postmark if transactional delivery is the whole job, you value separating broadcast from transactional traffic by stream, and a premium at small volume is acceptable.
• Look at both again around 300,000 a month. The price gap is gone, so the decision reverts to dedicated IP handling, support and webhook security.

Migrating between them

1. Create the destination account and authenticate your sending domain; on Postmark's Basic plan you have 5 custom sending domains to work with.
2. Separate traffic first. In Postmark create a transactional stream and a broadcast stream; in SendGrid decide which streams stay on the Email API and which belong to Marketing Campaigns.
3. Carry over suppressions: bounced, unsubscribed and spam-reported addresses must be loaded on the new side before the first send.
4. Rebuild templates and replay webhook payloads against the new event names. If moving to Postmark, replace signature checks with Basic Auth and an IP allowlist.
5. Shift traffic in stages over a week, watching bounces and complaints at each step, and export the old account's logs before closing it, since retention windows are short.

Related reading: Resend vs SendGrid, Resend vs Postmark, Postmark vs Mailgun, SendGrid vs SparkPost and Postmark vs Amazon SES.