Postmark vs SendGrid: Which Email Service Fits Your Mail Mix and Budget
Postmark or SendGrid for transactional and marketing email: what each is built for, what they cost at 10,000, 50,000 and 125,000 emails a month, and how to switch.
For a product team whose main need is password resets, receipts and login alerts arriving reliably, Postmark is the better pick, and its Basic plan lists at $15 a month for 10,000 emails. SendGrid is the better pick when the same account also has to send newsletters and bulk marketing mail: its Marketing Campaigns Basic plan lists at $15 a month for up to 100,000 contacts and 300,000 emails, and its Email API Essentials plan lists at $19.95 a month for 50,000 to 100,000 emails. The deciding question is whether your transactional and marketing mail can safely share one sending setup.
This guide explains what each service is built for, what it costs at three realistic monthly volumes, how the two differ on separating kinds of mail, and how to move from one to the other. Prices are the figures shown on each vendor's pricing page, checked on 7 October 2026. Where a page does not list a price for a given volume, the tables say so instead of estimating one.
The short version
Both services send email through an application programming interface, and both can send bulk mail. They differ in scope. Postmark is organised around transactional email, the messages an application sends when something happens to a user, and it offers only a limited broadcast option. SendGrid covers two jobs under one account: an Email API for transactional sends, and Marketing Campaigns for contact lists and newsletters. The table below sets out the differences that usually decide the choice.
| Question | Postmark | SendGrid |
|---|---|---|
| What it is built for | Transactional email, with a limited broadcast option | An Email API for transactional sends, plus Marketing Campaigns for newsletters and lists |
| Free option | 100 emails a month, no overages | Email API free trial of 100 emails a day for 60 days; Marketing Campaigns free plan of up to 2,000 contacts and 6,000 emails a month |
| Entry paid price | $15 a month, Basic plan, starting at 10,000 emails a month | $15 a month, Marketing Campaigns Basic, up to 100,000 contacts and 300,000 emails; $19.95 a month, Email API Essentials, 50,000 to 100,000 emails |
| How pricing is set | By email volume, with Basic, Pro and Platform tiers at each volume | By volume band for the Email API; Marketing Campaigns plans depend on both contact count and email volume |
| Separation of mail types | Message streams keep transactional and broadcast mail apart | One shared platform, so you set up the separation yourself |
| Main limitation | Marketing features are limited; no full campaign suite | More settings to learn, and the free tiers have time or size caps |
| Better for | Product email where separation from marketing sends matters most | Teams that send transactional and marketing mail and want one vendor account |
What Postmark is built around
Postmark is organised around transactional email: the messages your application sends in response to user actions. Password resets, one-time codes, order confirmations, invoices and system alerts are the core use. Its message streams let you keep those sends in a separate lane from broadcast mail such as a newsletter or a product update. The point of the separation is practical. A newsletter with weaker engagement, or a burst of complaints, should not be able to delay a password reset that a customer is waiting for.
Postmark does offer broadcast sending, but it is a secondary part of the product. It is not a full campaign suite with segmentation, automation builders or landing pages, and it is not positioned as a replacement for a dedicated marketing platform. Teams that want that kind of tooling usually pair Postmark with a separate marketing product and keep the two sending paths distinct.
What SendGrid is built around
SendGrid covers more ground. Its Email API handles transactional and programmatic sends, and Marketing Campaigns handles contact lists and newsletters. Both sit in one account with one set of credentials and one billing relationship. SendGrid is part of Twilio, so an organisation that already uses Twilio for SMS or voice can keep those services under one vendor, which some teams find useful for procurement and support.
The trade-off is that breadth brings complexity. Transactional and marketing mail share the same platform, so keeping them apart is a matter of configuration and discipline rather than a built-in lane. That is workable, but someone on your team has to own the rules: which sending domain or subuser carries which mail, which lists may be mailed, and how bounces and complaints are handled for each stream.
Postmark in detail
Where it fits: application teams that send mail triggered by user actions and need those messages to arrive quickly and reliably. If your product has a login flow, a checkout or a billing cycle, transactional mail is part of the product experience, and a slow or flagged campaign should not touch it.
What it does well for this audience: the message stream model is the clearest argument for Postmark. It makes the separation between critical and promotional mail a structural feature rather than something enforced by naming conventions. Its free plan of 100 emails a month with no overages lets a developer connect the service and send test messages before committing to a paid plan. The paid tiers keep the same product focus, so a team that grows does not have to change vendors to keep its transactional mail on a dedicated path.
Where it falls short: the free plan will not carry production traffic, so most real applications move to a paid tier quickly. Marketing is a secondary feature, so a team that wants segmentation, drip sequences and campaign reporting in one place will need a second product. Costs also rise faster with volume than SendGrid's bands do. At 50,000 emails a month, the Basic plan costs $55 on Postmark against $19.95 for the comparable Email API band on SendGrid, so the gap is large at moderate volumes.
Price: at 10,000 emails a month the Basic plan is $15, the Pro plan is $16.50 and the Platform plan is $18, with the monthly figures shown on the vendor's pricing page. At 50,000 emails a month, Basic is $55, Pro is $60.50 and Platform is $66. At 125,000 emails a month, Basic is $115, Pro is $126.50 and Platform is $138. The full plan details are on the Postmark pricing page.
SendGrid in detail
Where it fits: teams that send both transactional and marketing email and want them handled in one account, and teams sending at volumes where the cost of a per-email platform becomes a real line item. It also suits organisations that already buy Twilio services and prefer one vendor relationship.
What it does well for this audience: the Email API bands are the main reason to consider SendGrid for product mail. At 50,000 emails a month the Essentials band lists at $19.95, and at 125,000 emails the Pro band lists at $89.95. On the Marketing Campaigns side, the free plan covers up to 2,000 contacts and 6,000 emails a month, and the paid Basic plan lists at $15 a month for up to 100,000 contacts and 300,000 emails. A team that wants newsletters and product mail in one account can therefore compare both products on one vendor's pricing page.
Where it falls short: the Email API free trial is 100 emails a day for 60 days, so it is a time-limited test rather than a permanent free tier. The Marketing Campaigns free plan has a hard contact cap. Because the product covers more uses, it has more settings to learn, and the separation between transactional and marketing traffic is something you must design and maintain. Teams that need strict stream separation may find it harder to guarantee than Postmark's built-in structure allows.
Price: on the Email API, Essentials is $19.95 a month for 50,000 to 100,000 emails, and Pro is $89.95 a month for 100,000 to 2,500,000 emails, as shown in the plan selector. On Marketing Campaigns, Basic is $15 a month for up to 100,000 contacts and 300,000 emails, and Advanced is $60 a month for up to 200,000 contacts and 1,000,000 emails. Higher-volume Email API arrangements are priced on request. The current terms are on the SendGrid pricing page on Twilio's site.
Pricing at three realistic volumes
The table below compares the plans that cover each volume. SendGrid has two products with different price logic, so the table shows the Email API and Marketing Campaigns in separate columns. Where a product lists no price for a volume, the table says so.
| Emails per month | Postmark (monthly price) | SendGrid Email API (monthly price) | SendGrid Marketing Campaigns (monthly price) |
|---|---|---|---|
| 10,000 | Basic $15; Pro $16.50; Platform $18 | No band listed at this volume; the listed bands start at 50,000 emails | Basic $15, within 100,000 contacts and 300,000 emails. The free plan covers only 6,000 emails, so it does not reach this volume. |
| 50,000 | Basic $55; Pro $60.50; Platform $66 | Essentials $19.95 (50,000 to 100,000 band) | Basic $15, within 100,000 contacts and 300,000 emails |
| 125,000 | Basic $115; Pro $126.50; Platform $138 | Pro $89.95 (100,000 to 2,500,000 band) | Advanced $60, within 200,000 contacts and 1,000,000 emails |
Three points stand out. First, at 10,000 emails a month the Postmark Basic plan and the SendGrid Marketing Campaigns Basic plan list at the same $15, but they are different products. The Postmark figure applies to transactional mail, while the SendGrid figure applies to a marketing list with up to 100,000 contacts. Choosing on price alone at this volume would ignore that difference.
Second, at 50,000 emails a month the gap between Postmark Basic at $55 and SendGrid Essentials at $19.95 is $35.05 a month, or $420.60 a year. The difference is the monthly figures multiplied by twelve, using the listed prices only.
Third, at 125,000 emails a month, Postmark Basic at $115 compares with SendGrid Email API Pro at $89.95, a difference of $25.05 a month or $300.60 a year. Against SendGrid Marketing Campaigns Advanced at $60, the difference is $55 a month, or $660 a year, although that product's contact cap of 200,000 must also fit your list.
The lower SendGrid figures do not settle the choice by themselves. If your transactional mail needs the separation that Postmark provides, the lower price may cost you engineering time to build comparable separation on SendGrid. Put a rough value on that work before you compare invoices. Each volume above also assumes you choose the plan whose band matches your usage, so check the band edges against your own counts before you commit.
Reading the numbers for your own list
Price bands depend on two numbers: the emails you send in a month and, for Marketing Campaigns, the contacts you hold. Count both separately. A list of 80,000 contacts that receives two newsletters a month sends about 160,000 emails, which moves you out of the Marketing Campaigns Basic band because that band caps emails at 300,000 but the Email API band for 160,000 emails is in the Pro range. A transactional app with 8,000 users who each trigger several messages a day may send far more emails than its user count suggests. Estimate each stream on its own terms before you use the tables above.
Also check whether a plan is monthly or annual. The Postmark figures above are the monthly prices shown on its pricing page. Any annual discount is stated there, and this comparison does not apply one.
Deliverability and separation of mail types
Deliverability depends on your sending domain, authentication records, list hygiene and content as much as on the vendor you choose. Both services need the same basics in place: a sending domain you control, SPF and DKIM set up correctly, a DMARC policy you monitor, and a process for removing bounced and complaining addresses. A vendor cannot repair a list that has never been cleaned, and no comparison page can promise inbox placement.
The real difference is how each service keeps one kind of mail from affecting another. Postmark's message streams give a built-in separation between transactional and broadcast sending, so the reputation of a newsletter is kept apart from the reputation of password resets. On SendGrid you reach a similar result through your own configuration, for example by sending transactional and marketing mail from different sending domains or subusers, and by applying strict suppression rules to both. The separation is achievable, but you are responsible for setting it up and keeping it that way.
If a single bad campaign could delay a customer's login or receipt, that risk should decide the question. A sensible rule is that mail a customer is waiting for should never share a sending path with mail they did not ask for.
Which to choose: a decision table
Use the table below to match your situation to a pick. Each row names the condition, the service it points to and the reason.
| If you need | Pick | Because |
|---|---|---|
| Password resets, receipts and alerts that newsletters must never affect | Postmark | Message streams separate transactional and broadcast mail as part of the product |
| One account for transactional mail and newsletters | SendGrid | The Email API and Marketing Campaigns share one account and one billing relationship |
| A free start with a small contact list | SendGrid | The Marketing Campaigns free plan covers up to 2,000 contacts and 6,000 emails a month, while Postmark's free plan is limited to 100 emails a month |
| Around 50,000 to 125,000 product emails a month, with cost as the main concern | SendGrid | The listed Email API bands at those volumes are lower than Postmark's comparable plans |
| Around 10,000 transactional emails a month on a paid plan | Postmark | Basic lists at $15 a month for 10,000 emails, and the Email API bands listed start at 50,000 |
| A full campaign suite with segmentation and automation | Neither alone | Postmark's marketing features are limited, and SendGrid's campaign tooling is narrower than a dedicated marketing platform, so pair your sender with a marketing tool |
Setup and migration checklist
Moving between the two services is mostly a matter of re-pointing your application's sending calls and rebuilding your suppression and authentication setup. The steps below apply in either direction. Keep the old sending path live until the new one has run cleanly for several days, and move one message type at a time.
| Step | What to do | Check before you cut over |
|---|---|---|
| 1. Inventory your mail | List every message type your application sends, its trigger and its monthly volume | Each type is tagged as transactional or marketing |
| 2. Export suppression data | Export bounced, unsubscribed and complaining addresses from the current service | The new service holds the full list before any mail is sent |
| 3. Authenticate the domain | Add SPF and DKIM records for the new sender and confirm they validate | Test messages pass authentication at several mailbox providers |
| 4. Set up separation | On Postmark, create a message stream for each type; on SendGrid, send transactional and marketing mail from separate domains or subusers | Transactional and marketing mail cannot take the same sending path |
| 5. Rebuild templates | Recreate templates and check variables, links and plain-text versions | Rendered output matches the original on common email clients |
| 6. Wire up events | Point delivery, bounce and complaint webhooks at your application | Events from test sends reach the correct handler |
| 7. Cut over gradually | Move one message type at a time, starting with low-risk mail | Bounce and complaint rates stay within your normal range for several days |
| 8. Retire the old path | Stop sending from the old service once every type has moved | No scheduled jobs still call the previous API |
A common approach is to start with the mail that carries the least risk, such as a marketing announcement, and leave password resets and receipts for last. That way any configuration mistake shows up on mail that customers are not waiting for. When the critical messages move, keep the old path ready for a rollback until the first full billing or login cycle has passed.
How to choose in practice
Start with what your product cannot afford to lose. If a missed or delayed password reset would generate support tickets or lost customers, weigh Postmark's separation more heavily. If your largest cost is a large volume of newsletters and product updates sent to a growing list, SendGrid's bands and Marketing Campaigns plans will often come out cheaper, provided you are willing to build and maintain the separation yourself.
Next, look at your volume and your list. Below about 10,000 emails a month the monthly difference is small, and the decision should rest on separation and on the tooling you will actually use. Between 50,000 and 125,000 emails a month, the gap in listed prices is large enough to change the result. Above that range, neither table gives a complete Postmark figure for every volume, so check the current plan options on Postmark's pricing page or ask the vendor before you decide.
Finally, consider who will run the service. A small team with one developer may prefer the narrower product, because there are fewer settings to get wrong. A team with an operations function that already manages sending domains, suppression lists and compliance may find SendGrid's breadth manageable and useful. The main link between the two is the same in both cases: one owner for suppression rules and sending domains.
For a broader view of how dedicated marketing platforms compare with sending services like these, see the comparison hub, which covers the wider market.
Common mistakes when comparing or switching
The most frequent error is comparing the cheapest plan at one volume and ignoring the plan the product will actually need. Check whether your volume falls within a band, whether your contact count changes the price, and whether a free tier is a permanent plan or a trial. The Email API free trial and the Marketing Campaigns free plan are separate products with separate limits.
The second error is copying the old sending setup without checking the new one's authentication. A new domain or subdomain starts with no sending history, so warm it up gradually rather than sending the full volume on the first day. Mailbox providers judge a new sender on its early behaviour, and a sudden spike can look like abuse.
The third mistake is treating suppression lists as optional. Bounces and complaints that are not removed from the old service may be imported into the new one by accident, or not imported at all, and either outcome harms reputation. Export, reconcile and import these lists deliberately, and keep a dated record of each import.
Frequently asked questions
Is Postmark or SendGrid cheaper for 10,000 emails a month?
It depends on which SendGrid product you mean. Postmark's Basic plan lists at $15 a month for 10,000 emails. SendGrid's Marketing Campaigns Basic plan also lists at $15 a month for up to 100,000 contacts and 300,000 emails, but it is built for marketing lists rather than application mail. The Email API bands listed start at 50,000 emails a month, so for transactional mail at this volume Postmark is the more direct comparison.
Is SendGrid cheaper at higher volumes?
On the listed figures, yes. At 50,000 emails a month, Postmark's Basic plan is $55 against SendGrid's Essentials band at $19.95. At 125,000 emails a month, Postmark's Basic plan is $115 against SendGrid's Pro band at $89.95. The gap is clearest at those volumes, but the right answer for your team also depends on what it will cost to set up separation of mail types yourself.
Does Postmark have a free plan?
Yes. Postmark's free plan allows 100 emails a month with no overages. It suits testing and very small volumes, and most production applications will need a paid plan.
Does SendGrid have a free plan?
SendGrid offers two free options. The Email API free trial allows 100 emails a day for 60 days. The Marketing Campaigns free plan allows up to 2,000 contacts and 6,000 emails a month. These are separate products with different limits, so check which one fits your use.
Can I use Postmark for newsletters?
Postmark offers a limited broadcast option, but it does not provide a full campaign suite with segmentation, automation or landing pages. Many teams send transactional mail through Postmark and run newsletters through a dedicated marketing platform, keeping the two sending paths separate.
What is the main difference between Postmark's message streams and SendGrid's setup?
Postmark's message streams separate transactional and broadcast mail as part of the product's structure. On SendGrid, both kinds of mail share one platform, so you keep them apart through your own configuration, such as separate sending domains or subusers. Both approaches can work. The first is enforced by the product, while the second depends on how carefully your team maintains it.
Which should a team with no marketing function choose?
If the team's only sending is product email, such as password resets, receipts and alerts, Postmark's narrower focus is usually the simpler choice, and its Basic plan lists at $15 a month for 10,000 emails. A team that expects to add newsletters later should also look at SendGrid's Marketing Campaigns plans, since they keep both kinds of mail in one account.