Mailgun

Mailgun is one of the original transactional email APIs and still one of the few platforms built for engineers first. It is the infrastructure layer for product and lifecycle email, not a marketing suite with an API stapled on the side.

What Mailgun Does

Mailgun is structured as four products that share one sending platform. Each one solves a different layer of the email problem, and together they cover almost everything a sending team needs outside of a CRM.

• Send: the core HTTP API and SMTP relay. Batched sends up to 1,000 personalised messages per call, webhooks for every event, and isolated sub-accounts per domain or product line.
• Validate: real-time and bulk email verification. Filters dead, role-based, and disposable addresses before they hit your sending queue.
• Optimize: deliverability tooling including inbox placement tests, blocklist monitoring, send-time optimisation, and a managed warmup path for dedicated IPs.
• Inspect: email rendering and accessibility testing across clients and devices, built on the Email on Acid engine Sinch acquired.
• Inbound routing: parses incoming mail into UTF-8 JSON and posts it to a webhook URL, so replies and ticket mailboxes become normal events.
• Analytics and logs: open, click, bounce, complaint, and delivery events with up to 30 days of retention on the higher tiers.
• Compliance: SOC 2 Type II, ISO 27001, HIPAA-ready BAAs, GDPR, and PCI SAQ-A merchant status.

Mailgun's Deliverability Layer

Mailgun's edge over generic SMTP is the Optimize layer. Inbox placement testing, send-time optimisation, blocklist alerts, and IP warmup are wired into the same dashboard as sending. For teams that have ever lost a week to a sudden Gmail block, that is the difference between a platform and a relay. Sinch's deliverability consulting team also sits behind Enterprise plans for senders who need a human in the loop.

Automations We Build with Mailgun

Mailgun sits at the edge of the stack, which means it touches almost every other system. We use it as the send and receive layer for product email, lifecycle, and operational mailboxes. The plays we run most often:

• Pre-send list scrubbing. Every list export from HubSpot, Salesforce, or the product database is pushed through the Validate API before it reaches Mailgun's send queue. Bounce rates typically drop below 1%.
• Event-driven lifecycle email. Mailgun receives sends from n8n or a serverless worker that watches Stripe, the product database, and the CRM. Trials, dunning, renewals, and win-back all fire from real events rather than a marketing schedule.
• Inbound parsing into the CRM. Replies to outbound sequences, support@ and billing@ mailboxes get routed to webhooks that classify the message and write it back to the right contact in HubSpot or Salesforce.
• Bounce and complaint loops. Hard bounces and spam complaints are pulled from Mailgun's event webhooks into Supabase, then synced back to suppress lists and CRM properties. No human ever re-mails a dead address.
• Dedicated IP traffic shaping. Transactional, lifecycle, and bulk marketing go through separate IP pools and sub-accounts. A bad marketing send cannot drag password reset deliverability with it.
• Send-time optimisation by segment. Mailgun's per-recipient scheduling plus our own engagement model decide when each contact gets the email, rather than blasting everyone at 09:00.

Why Teams Choose Mailgun

• API-first design. Mailgun was built around the API, not a marketing UI. Setup, sub-accounts, suppression lists, and analytics are all reachable from code.
• Burst capacity without surprises. The platform handles tens of millions of messages per hour, with documented SLAs for high-volume senders.
• Validation is native, not a separate vendor. Most stacks bolt on Kickbox or NeverBounce. With Mailgun, validation runs on the same platform as sending.
• Deliverability help when you need it. Sinch's deliverability team is reachable on Scale and Enterprise plans, which matters the first time a major mailbox provider throttles you.
• Compliance posture for regulated buyers. SOC 2, ISO 27001, GDPR, HIPAA, and PCI SAQ-A all in one platform shortens security review for healthcare, fintech, and enterprise deals.

Mailgun integrates with most of the stack a mid-market team already runs: Stripe and Salesforce through native or community libraries, Segment, MailerLite, HubSpot, n8n, Zapier, and any system that can hit a webhook. Pricing starts at $15 per month for the Basic plan (10,000 emails), $35 for Foundation (50,000 emails), and $90 for Scale (100,000 emails plus dedicated IP pools and validation credits), with Enterprise quoted for high-volume senders. That is the platform. The automations on top of it are the build we do.