Mailgun
Developer-first transactional email API with inbound routing, email validation, and deliverability tooling at scale.
Acquired — still operating
Mailgun was acquired by Sinch in 2021 and continues to operate as a Sinch product; marketing email is handled via sister brand Mailjet.
About
Mailgun is a transactional email API for engineering-led teams, owned by Sinch since its 2021 acquisition. It covers the full sending workflow: REST and SMTP sending, inbound email parsing that turns incoming mail into webhooks (useful for support tickets and email-to-API flows), a built-in email validation API, send-time optimization, and deliverability tooling including EU data residency, ISO 27001 certification, and a HIPAA BAA for regulated sends. Mailgun's Rapid Fire Delivery SLA targets attempting 99% of accepted messages within 5 minutes.
Pricing starts with a free tier of 100 emails per day, then Basic at $15/month (10,000 emails), Foundation at $35/month (50,000), and Scale at $90/month (100,000) with a dedicated IP included; overages run $1.10-$1.80 per 1,000 depending on tier, and Enterprise is custom. The catch reviewers consistently flag is log retention: one day on Free and Basic, five on Foundation, and 30 only on Scale, so debugging last week's delivery problem on a $15 plan is not possible.
What it can do
- REST API and SMTP relay
- Inbound email parsing (Routes)
- Email validation API
- Send-time optimization
- Dedicated IPs
- EU data residency option
- ISO 27001 and HIPAA BAA support
- Detailed delivery logs and webhooks
- Multiple official SDKs
Setup
Create a Mailgun account, verify a sending domain with DNS records, and integrate via the REST API, SMTP, or an official SDK.
Prerequisites
Verified sending domain; developer to integrate the API/SDK; compliance with the Acceptable Use Policy (no cold email).
Use cases
Works with
Trust score — 7/10
Scored 7/10 (TIER metrics, metrics-v1). Evidence: Sinch ownership since 2021 and pricing tiers verified across three independent 2026 comparisons (Courier, MailerCloud); G2 4.5 cited by Courier. Strengths: most complete toolkit around the API (validation, inbound routing, deliverability controls), usage-based pricing, compliance posture. Docked for: (1) log retention of 1 day on entry plans makes debugging hard; (2) delivery-speed SLA claims are provider-stated without published independent measurements; (3) complex tier structure makes total cost harder to forecast. License: proprietary SaaS; free tier, paid from $15/month.
How the trust score is built
Full methodology →- Adoption · stars/downloads, log-scaled vs peers
- 8.0/10
- Maintenance · recency, releases, issue load
- 8.0/10
- Openness · license + docs
- 4.0/10
- Manual review · sanity read + red-flag check
- 8.0/10
- · Acquired by Sinch in 2021; operates as a Sinch product
- · G2 4.5 cited by Courier comparison
- · Most complete toolkit around the API: validation, inbound routing, deliverability
- · Log retention only 1 day on Free/Basic — debugging handicap
- · Complex tier structure makes total cost harder to forecast
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.