Postmark vs Mailgun for Solo Developers

Quick Comparison

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 trial gives you a sandbox for testing, and the Flex plan starts at $0 but limits you to a shared IP and 5,000 emails. The Foundation plan at $35/month gets you 50,000 emails with dedicated IP options. 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. Postmark charges $15/month for 10,000 emails with no setup fees and no contracts. Mailgun's Foundation plan is $35/month for 50,000 emails. If you send fewer than 10,000 emails monthly, Postmark is cheaper and simpler. If you send more, Mailgun's per-email cost is lower at scale.

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.

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.