Postmark vs Mailgun for Solo Developers

Comparing Postmark and Mailgun for solo developers. Features, pricing, pros and cons, and which one to pick for your next project.

Quick Comparison

Feature	Postmark	Mailgun
Type	Transactional email delivery	Transactional + bulk email API
Free tier	100 emails/month, never expires	100 emails/day
Entry paid plan	Basic, $15/mo for 10,000 emails	Basic, from $15/mo for 10,000 emails
Overage (entry plan)	$1.80 per 1,000 emails	$1.80 per 1,000 emails
Log/data retention (entry)	45 days	1 day
Node SDK version	postmark 4.0.7	mailgun.js 13.1.0
Node SDK GitHub stars	358	547
npm downloads (week of May 21 to 27, 2026)	859,142	825,643
Learning Curve	Very Easy	Moderate
Best For	Reliable transactional email with fast delivery	Flexible email sending with routing and validation
Solo Dev Rating	9/10	7/10

Postmark Overview

Postmark is laser-focused on transactional email, and that focus pays off. When you send a password reset, a receipt, or a signup confirmation through Postmark, it arrives in the inbox within seconds. Not minutes. Seconds. That speed comes from Postmark's strict policy: they only allow transactional email. No newsletters. No marketing blasts. No bulk promotions. This keeps their sending reputation pristine, which means your emails land in inboxes, not spam folders.

The developer experience is excellent. The API docs are some of the best I have seen in any SaaS product. You set up domain verification, grab your API key, and start sending with a single API call. Postmark also has message streams, which let you separate transactional and broadcast emails into isolated channels with their own deliverability stats. Templates are managed in the dashboard with a clean editor, and they support both HTML and plain text previews.

For a solo developer shipping a product, Postmark removes all the worry about email delivery. You call the API, the email arrives instantly, and you move on to building features.

Mailgun Overview

Mailgun is a Sinch-owned email platform that handles transactional, bulk, and marketing email. It started as a developer-focused API and has grown into a full email delivery suite with validation, routing, and analytics. If Postmark is a scalpel, Mailgun is a Swiss Army knife.

The feature set is broad. Email validation catches bad addresses before you send. Inbound routing lets you receive and parse incoming emails programmatically. Mailing list management handles subscriber groups. The API supports SMTP and REST, and there are SDKs for every major language. Mailgun also offers email logs, analytics, and webhooks for delivery events.

Mailgun's free plan gives you a sandbox for testing capped at 100 emails per day with 1 day of log retention. The Basic plan starts at $15 per month for 10,000 emails, Foundation is $35 per month for 50,000 emails with 5 day log retention and 5,000 included validations, and Scale at $90 per month bumps you to 100,000 emails, 30 day log retention, and one dedicated IP included. For solo developers who need more than just transactional email, Mailgun provides the flexibility without needing multiple tools.

Key Differences

Deliverability is Postmark's strongest selling point. Because Postmark refuses bulk and marketing email, their IP reputation stays clean. Average delivery time is under 10 seconds. Mailgun handles all email types on shared infrastructure, which means your transactional emails share IP space with other senders' marketing blasts. You can buy a dedicated IP from Mailgun, but that costs extra and requires enough volume to warm it properly.

Scope of features. Mailgun does more. Inbound email parsing, mailing lists, email validation, and SMTP relay all come built in. Postmark is transactional only. If you need to receive and process incoming emails (like a support ticket parser), Mailgun handles that. Postmark added inbound processing but it is more limited.

Pricing structure. As of early 2026 both services anchor at the same entry point. Postmark's Basic plan is $15 per month for 10,000 emails with no setup fees and no contracts, and Mailgun's Basic plan also starts at $15 per month for 10,000 emails. The overage rate on those entry plans is identical too at $1.80 per 1,000 emails. The two diverge above 10,000 sends per month. Postmark keeps you on a 10,000 included plan and charges overages, with the Pro tier at $16.50 per month dropping the overage to $1.30 per 1,000 and the Platform tier at $18 per month dropping it to $1.20 per 1,000. Mailgun instead steps you up to Foundation at $35 per month for 50,000 emails, then Scale at $90 per month for 100,000 emails. So at high volume Mailgun's bundled pricing is cheaper per email, while at low and predictable volume the two are now effectively a wash on price and the decision comes down to features and retention. One nuance worth knowing: Postmark's Basic plan keeps 45 days of message history, while Mailgun's Basic plan keeps only 1 day, so if you debug deliverability by reading old logs that retention gap matters more than the matching sticker price.

Dashboard and analytics. Postmark's dashboard is clean and focused. You see delivery stats, bounces, and spam complaints at a glance. Mailgun's dashboard has more data points but feels busier. Both offer webhooks for programmatic event tracking.

Template management. Postmark has a built-in template system with variables and layouts. Mailgun supports templates too, but the workflow is more manual. Neither matches the developer experience of something like React Email, but Postmark's template system is more polished out of the box.

By the Numbers (2026)

Here is the verified, current state of both services, checked against vendor pricing pages, the public package registries, and the official SDK repositories on 2026-05-29.

Postmark

Free plan: 100 emails per month, never expires, no overages allowed on this plan.
Basic plan: $15 per month, 10,000 emails included, $1.80 per 1,000 overage, 45 day data retention.
Pro plan: $16.50 per month, 10,000 emails included, $1.30 per 1,000 overage, retention customizable up to 365 days.
Platform plan: $18 per month, 10,000 emails included, $1.20 per 1,000 overage, retention customizable up to 365 days.
Official Node SDK: postmark version 4.0.7 on npm, MIT licensed, published by ActiveCampaign.
SDK GitHub repo: ActiveCampaign/postmark.js, 358 stars, 40 forks, last pushed 2026-05-08.
npm downloads: 859,142 in the week of 2026-05-21 to 2026-05-27, roughly 3.68 million in the trailing month.

Mailgun

Free plan: 100 emails per day, 1 day log retention, validations available as an add-on.
Basic plan: from $15 per month, 10,000 emails included, $1.80 per 1,000 overage, 1 day log retention.
Foundation plan: $35 per month, 50,000 emails included, $1.30 per 1,000 overage, 5 day log retention, 5,000 validations included.
Scale plan: $90 per month, 100,000 emails included, $1.10 per 1,000 overage, 30 day log retention, one dedicated IP included.
Official Node SDK: mailgun.js version 13.1.0 on npm, MIT licensed, requires Node 18 or newer.
SDK GitHub repo: mailgun/mailgun.js, 547 stars, 109 forks, last pushed 2026-05-22.
npm downloads: 825,643 in the week of 2026-05-21 to 2026-05-27, roughly 3.86 million in the trailing month.

The two SDKs are close in adoption. Mailgun's package has more GitHub stars and slightly more weekly npm pulls, while Postmark's package sees marginally higher monthly downloads. Neither is a small or abandoned library, and both were pushed within the last month, so on integration health you are safe either way.

Real Cost at Solo-Dev Scale

Pricing pages list rates. What you actually care about is the monthly bill for your real workload, so here is the math for two concrete solo-dev scenarios using the verified rates above.

Assumptions. Scenario A is a small SaaS sending purely transactional email: signup confirmations, password resets, and receipts, totalling 8,000 emails per month. Scenario B is a growing product that has added a weekly product update broadcast on top of transactional, totalling 45,000 emails per month. All figures use the published 2026 rates and assume no dedicated IP unless the plan bundles one.

Scenario A, 8,000 emails per month.

Postmark Basic: $15 flat. The plan includes 10,000 emails, so 8,000 sits inside the allotment with no overage. Monthly cost $15.
Mailgun Basic: $15 flat. The plan also includes 10,000 emails, so 8,000 is inside the allotment with no overage. Monthly cost $15.

At this volume the two are identical on price, $15 per month. The tiebreaker is the 45 day versus 1 day log retention and Postmark's transactional-only deliverability posture, both of which favor Postmark for a pure transactional workload.

Scenario B, 45,000 emails per month.

Postmark: the included allotment is 10,000, so you pay for 35,000 emails of overage. On Basic at $1.80 per 1,000 that overage is $63.00, for a total of $15 + $63.00 = $78.00 per month. On the Platform plan at $18 per month with a $1.20 per 1,000 overage, the 35,000 overage costs $42.00, for a total of $18 + $42.00 = $60.00 per month, which is the cheaper Postmark path at this volume.
Mailgun Foundation: $35 flat includes 50,000 emails, so 45,000 sits inside the allotment with zero overage. Monthly cost $35.

At 45,000 emails per month Mailgun Foundation at $35 is meaningfully cheaper than the best Postmark configuration at $60, because Mailgun bundles a much larger allotment into a single flat tier. The crossover happens once your volume climbs past the 10,000 Postmark includes, since Postmark monetizes the overflow per thousand while Mailgun sells you a bigger bucket. If your sending is mixed transactional and broadcast and growing, that bundled volume is the financial case for Mailgun. If you are firmly under 10,000 emails per month and only send transactional, the bill is a wash and you should pick on deliverability and retention instead of price.

When to Choose Postmark

Deliverability is your top priority and you want emails arriving in seconds
You only need transactional email (receipts, resets, notifications)
You send under 10,000 emails per month and want simple, predictable pricing
You value clean documentation and fast integration
You want peace of mind that email delivery just works without tuning

When to Choose Mailgun

You need both transactional and bulk/marketing email from one platform
You want inbound email parsing for receiving and processing emails
You need email validation to clean your user list before sending
You send high volumes where Mailgun's pricing scales better
You need SMTP relay as a fallback alongside the REST API

The Verdict

For most solo developers, Postmark is the better choice. You are probably sending transactional emails: welcome messages, password resets, payment receipts, and notifications. Postmark does this better than anyone. The delivery speed is noticeable, the setup takes minutes, and you never worry about your emails landing in spam.

If your project needs more than transactional email, like receiving inbound emails, managing mailing lists, or sending marketing campaigns alongside transactional messages, Mailgun's breadth makes it the smarter pick. Just budget time for deliverability tuning that Postmark handles automatically.

My recommendation: start with Postmark for transactional email. If you later need marketing email, pair it with a dedicated tool like Loops or Buttondown rather than trying to make one platform do everything. Specialization wins when you are building alone.