Guide

Mailgun vs Nylas: When to Use Each

Mailgun and Nylas both say 'email API,' and developers pick the wrong one about half the time. Mailgun sends and routes mail from a domain you own — high-volume outbound plus inbound routing rules. Nylas reads and sends from a user's own mailbox across six providers. They solve opposite halves of the email problem. This compares them so you buy the half you actually need.

Written by Pouya Sanooei Software Engineer

Verified — CLI 3.1.16 · Gmail, Outlook · last tested June 8, 2026

Command references used in this guide: nylas email send, nylas email list, and nylas email search.

What is the difference between Mailgun and Nylas?

Mailgun is a developer-focused email service for sending and receiving mail from a domain you own. It sends transactional and bulk email through its SMTP and HTTP APIs, signs with DKIM, tracks bounces, and — through inbound routing rules — converts mail received at your domain into HTTP POSTs. Nylas is a contextual email API: it connects to a user's existing mailbox over OAuth and reads, searches, and sends from their address.

Mailgun, now part of Sinch after the 2021 acquisition, prices outbound on a pay-as-you-go model documented on the Mailgun pricing page. Nylas bills per connected account, because its value is inbox access rather than send volume. Mailgun sends from noreply@yourapp.com; Nylas works inside user@theircompany.com.

How do Mailgun and Nylas compare feature by feature?

The table compares both across nine dimensions. Mailgun leads on outbound volume and inbound routing at your own domain; Nylas leads on reading user inboxes, calendar, and provider coverage. The shared capability is sending — Mailgun from your domain, Nylas from the user's.

DimensionMailgunNylas
CategorySending + inbound routingContextual email API
Send emailYes (from your domain)Yes (from user's inbox)
Read a user's inboxNoYes (6 providers)
InboundRouting rules (your domain)Webhooks on user mailbox
Calendar / contactsNoYes
PricingPay-as-you-go per messagePer connected account
AuthAPI keyOAuth 2.0 (user authenticates)
Email validationYes (built-in service)No
CLINo first-party CLIYes (open source)

When should you use Mailgun?

Use Mailgun when your application sends high volumes of mail from your own domain and you want strong developer tooling around it. Notifications, receipts, and marketing campaigns fit, and Mailgun adds email validation and detailed analytics that suit teams optimizing deliverability. Its inbound routing — documented in the Mailgun receiving docs — matches incoming mail at your domain against rules and forwards it as an HTTP request.

That inbound routing is for domains you control, not for reading someone's Gmail. If your feature is “receive support email at help@yourapp.com and POST it to our app,” Mailgun is a clean fit. If it's “read the customer's own inbox,” routing rules can't reach it. Mailgun has no concept of a connected user account or OAuth-based inbox access.

# Mailgun — send a transactional email (HTTP API, curl)
curl -s --user 'api:YOUR_API_KEY' \
  https://api.mailgun.net/v3/yourdomain.com/messages \
  -F from='noreply@yourdomain.com' \
  -F to='user@example.com' \
  -F subject='Your code: 731904' \
  -F text='This code expires in 10 minutes.'

When should you use Nylas?

Use Nylas when your application has to work inside a user's real mailbox. A CRM that logs the thread with a customer, an AI agent that triages a support inbox, or a scheduler that sends invites from the rep's own calendar all need contextual access Mailgun can't provide. The user authenticates once over OAuth, and your app reads and sends on their behalf across Gmail, Outlook, Exchange, Yahoo, iCloud, and IMAP.

The CLI makes that testable in about two minutes. After nylas auth login, you can read the inbox, search by sender, and send from the connected account, with --json output for scripts and AI pipelines. There's no domain to verify and no routing rule to write, because Nylas reads the mailbox the user already owns.

# Nylas — read and send from the user's own mailbox
nylas auth login --provider google
nylas email search "from:customer@acme.com" --json --limit 20
nylas email send --to customer@acme.com \
  --subject "Re: your ticket" --body "Replying from my own inbox."

Many apps run both: Mailgun for outbound notifications and inbound routing at your domain, Nylas for the customer-facing inbox. The dividing line is the same as the rest of this category — noreply@yourapp.com is Mailgun; user@theircompany.com is Nylas. See the full email API comparison for where SES, SendGrid, Resend, and Postmark fit.

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