Postal vs Mailgun
Both are alternatives to SendGrid. Here's how they stack up — verified facts, no spin.
Also searched as Mailgun vs Postal — same comparison, one verdict.
Postal is open source (MIT) and Mailgun is not (Proprietary (hosted service)) — so the real question is whether you want to own the transactional & bulk email stack or rent it.
Postal
Run your own mail server, properly — MIT, and complete.
Postal is a full self-hosted mail platform: sending, receiving, bounce handling, click and open tracking, DKIM signing and a web interface — the parts you would otherwise assemble from Postfix, OpenDKIM and a database. MIT, around 17k stars. It is the only option here where addresses never leave your infrastructure, which for GDPR-sensitive senders is not a preference but a requirement. The honest warning: running a mail server well is a real discipline, and reputation is unforgiving of mistakes.
Mailgun
The established competitor — strong on validation and routing.
Mailgun is SendGrid's long-standing rival with a comparable feature set and reputation, plus two things it does distinctly well: email address validation before you send, and inbound routing that parses received mail into your application. Proprietary and hosted, priced per volume with a small free allowance. Listed for the same reason as Render on the Heroku page — many teams comparing this category are choosing between managed vendors, and the honest comparison includes the obvious alternative rather than assuming everyone will self-host.
Side by side
6 points of comparison, every one read from a verified field. Green marks the side that wins a row outright. A dash means we do not hold that fact — never that it is zero.
| Postal | Mailgun | |
|---|---|---|
| Sovereignty ScoreOur transparent 0–100 composite for data ownership and exit cost. | 94 | 31 |
| Open source | Yes | No |
| Self-hostable | Yes | No |
| Local-first data | Yes | No |
| License | MIT | Proprietary (hosted service) |
| Pricing | Free and open source. You supply the server and the IP reputation. | Volume-based with a small free allowance; paid tiers from about $15/month. Checked 2026-08-05. |
Postal edges it on the Sovereignty Score, but the right pick depends on the trade-offs below.
Weighing both against staying on SendGrid? Is SendGrid free? What it actually costs →
Postal
Strengths
- +MIT with no enterprise carve-out
- +Recipient addresses never leave your infrastructure
- +Full platform — sending, receiving, bounces, tracking, DKIM
- +No per-email cost at any volume
Trade-offs
- −You own IP reputation, and warming takes weeks of care
- −Running mail well is a genuine specialism
- −Blocklists are unforgiving of configuration mistakes
- −No shared warmed pool to fall back on
Mailgun
Strengths
- +Strong deliverability record over many years
- +Address validation catches bad addresses before you send
- +Genuinely good inbound routing and parsing
- +Detailed logs and analytics
Trade-offs
- −Proprietary and hosted
- −More expensive than SES for straightforward transactional mail
- −Pricing tiers are harder to read than they should be
- −Support quality varies by plan
Which one fits you
The trade-offs above, turned into a decision. Find the line that describes your team.
Choose Postal
if you want the source and the option to fork it, and you would rather run it on your own hardware, and your data should stay on machines you control.
Choose Mailgun
if strong deliverability record over many years.
Neither, yet
if both carry a real cost you should weigh first — you own IP reputation, and warming takes weeks of care, and proprietary and hosted. If either of those is a dealbreaker for your team, the shortlist is wrong rather than the choice.
Postal vs Mailgun — common questions
Is Postal a better fit than Mailgun for transactional & bulk email?
It depends on what you are optimising for, and the honest split is this: Postal scores 94 to Mailgun's 31 on data ownership and exit cost, so it is the safer choice if you care about being able to leave. Mailgun earns its place on a different axis — strong deliverability record over many years. Neither is a wrong answer for every team; the table above is the actual comparison.
What happens if we want to switch later?
Postal keeps its data local or in open formats, so leaving is an export rather than a negotiation. Mailgun keeps your data on its own infrastructure, which is the part to plan for: confirm the export path before you commit, not when you are already trying to leave.
Can I self-host Postal?
Postal can be self-hosted; Mailgun cannot, so it stays on the vendor's infrastructure whatever you do.
Are Postal and Mailgun both alternatives to SendGrid?
Yes — both appear in our SendGrid comparison, which is why they are worth putting side by side. People usually arrive here already having decided to move off SendGrid and now choosing between the two replacements, which is a narrower and much easier question.
Related alternative guides
Facts verified 2026-09-27. Licenses and pricing change — spotted something out of date? That's a correction we want.