Stack
Mailgun
An email sending API and SMTP relay aimed at developers who need programmatic sending and inbound routing.
What it actually does
Mailgun is email plumbing for engineers: a sending API and SMTP relay with strong routing and inbound parsing, so an app can both send and receive mail programmatically without a marketing suite bolted on.
The permanent free tier allows 100 emails/day, roughly 3,000/month, enough for an MVP's auth email. Paid plans step up through Foundation (50,000 emails, 5-day logs) to Scale (100,000 emails, dedicated IP).
The main catch is log retention: Free and Basic keep only one day of logs, so investigating yesterday's bounce means moving to a $35/mo plan. There is no real marketing product; campaigns require the sibling tool Mailjet as a second subscription.
Mailgun vs its main rivals
The tools people actually weigh against Mailgun: Amazon SES, SendGrid, Postmark. Same criteria for every column, including where Mailgun loses.
| Mailgun | AAmazon SES |  SendGrid | ||
|---|---|---|---|---|
Pricing & access | ||||
| Free tier | Yes100/day | NoNo | No60-day trial | Yes100/mo |
| Starting price | $15/mo | $0.10/1k | $19.95/mo | $15/mo |
Deliverability & sending | ||||
| Independent inbox-placement score | ~71% | ~77% | ~61% | ~83% (top) |
| Inbound routing / parsing | YesStrong | YesVia SNS | YesYes | YesYes |
| SMTP relay | YesYes | YesYes | YesYes | YesYes |
Scaling & limits | ||||
| Overage rate | $1.80/1k | $0.10/1k | $1.30/1k | $1.80/1k |
| Log retention (entry plans) | 1 day | CloudWatch | Varies | 45 days |
| Dedicated IP available | YesScale plan | YesAdd-on | YesPro plan | YesAdd-on |
Developer & API | ||||
| REST API | Free | Free | Free | Free |
| Email validation | YesAdd-on | NoNo | YesPro | NoNo |
Team & enterprise | ||||
| SSO / SAML | YesEnterprise | YesAWS IAM | YesPro+ | YesEnterprise |
- Permanent free tier at 100 emails/day, enough for an MVP's auth email
- Strong sending API with good routing and inbound parsing for the price
- Foundation plan bundles 50,000 emails, 5-day logs, and validations
- Log retention is 1 day on Free and Basic, so debugging older bounces needs a $35/mo plan
- Basic overage of $1.80 per 1,000 is twice Resend's rate
- No real marketing suite; campaigns need the separate Mailjet subscription
Pay less for it
5 ways found100 emails/day covers an MVP's auth and reset email at no cost.
The $35/mo Foundation plan unlocks 5-day logs and email validation, worth it once you need to debug bounces.
Paying yearly lowers the effective monthly rate versus month-to-month plans.
At high volume SES at ~$0.10 per 1,000 undercuts Mailgun's $1.80 overage by roughly 18x.
Amazon SES — Far cheaper per email for high-volume transactional sending if you can build your own routing, logs, and analytics on top.
StackTracker tracks what you actually pay for Mailgun and every other tool, flags overpayment, and shows the dollars you would save by switching.
Is it the right tool for you
- You want raw SMTP/API sending plus inbound routing cheaply
- You are backend-heavy and do not need a marketing UI
- An MVP's auth email fits inside 100/day free
- You need to investigate delivery issues days later → use Postmark (45-day logs)
- You want top transactional inbox placement → use Postmark
Track what Mailgun and the rest of your stack cost
StackTracker adds up every subscription, plus your hours, so you see the real number.
Prices and limits last verified 2026-07-20.