The Mailgun playbook

Mailgun sends the API calls. Your domain still has to earn the inbox.

Mailgun warms dedicated IPs automatically, but its own guidance says a new domain will most likely need warming itself. Keep sending through the Mailgun API or SMTP exactly as you do now. Add your brand domain here and we build its reputation while Mailgun keeps sending.

Start warming my domainSee Inbox Boost
The Mailgun playbook

Keep sending from Mailgun. Warm the domain here.

Step 1

Add and verify your own domain in Mailgun

Every account starts with a sandbox domain that is for testing only and delivers just to Authorized Recipients. Real sending needs your own domain, verified with the SPF and DKIM TXT records shown in the control panel. Until they verify, Mailgun holds the domain to a daily sending cap.

Step 2

Know what Mailgun warms, and what it does not

Automatic IP Warmup raises the limits on a dedicated IP in stages and rolls the overflow onto your other IPs. It warms the IP. Mailgun’s own guide says domain reputation is separate and a new domain will most likely need warming itself, and each Mailgun domain, subdomains included, gets its own DKIM authority.

Step 3

Add your brand domain to Inbox Boost

Use the domain in your From address, such as yourapp.com. The sending subdomain Mailgun uses, such as mg.yourapp.com, stays with Mailgun. We set up what the domain needs and build its sender reputation for you. Nothing to connect to Mailgun: no API key, no webhook, no change to your account.

Step 4

Keep every API call and SMTP send on Mailgun

Password resets, receipts, notifications: all of it stays on Mailgun. Mailbox providers score the domain in your From address, so the reputation built here counts for every Mailgun send from yourapp.com.

Step 5

Check where Mailgun mail lands

Inbox placement tests show whether your application mail reaches the inbox or Spam across the major mailbox providers, and blacklist monitoring keeps watching the domain once it is warm.

  • Nothing to connect: no Mailgun API key, webhook or integration
  • Nothing to change: your code, SMTP credentials and templates stay exactly as they are
  • Shared or dedicated IP: it works either way, because the reputation belongs to the domain
  • Watched after warmup: blacklist and authentication monitoring on your brand domain
Features Mailgun senders lean on

The parts of the platform this plan leans on.

Feature

Inbox Boost

Add a domain. We provision the sending server and publish your DNS.

Learn more Feature

Guided DNS setup

We write SPF, DKIM and return-path into your zone, not you.

Learn more Feature

Inbox placement testing

See whether you land in Primary, Promotions or Spam across providers.

Learn more
See it play out

A Mailgun domain, warmed without pausing a single send.

Four checkpoints, in order. Click any step or let it play.

mailgun · mg.yourapp.com
SPF (TXT)verified
DKIM (TXT)verified
sending historynone yet
Questions

Mailgun questions, answered.

Does Inbox Boost connect to my Mailgun account?
No. There is no API key, webhook or integration to set up. Inbox Boost works on your brand domain, and Mailgun keeps sending your application mail exactly as it does now.
Mailgun already warms dedicated IPs. Why warm the domain too?
Automatic IP Warmup raises the limits on a dedicated IP in stages. Your sending domain carries its own reputation with Gmail, Outlook and Yahoo, and Mailgun’s own warm-up guide says domain reputation is separate from IP reputation and that a new domain will most likely need warming itself.
I am on Mailgun’s shared IPs. Does this still help?
Yes. Automatic IP Warmup only applies to dedicated IPs, and on shared IPs the IP reputation is pooled with other Mailgun senders, so the domain is the reputation that is actually yours. Building it here helps everything Mailgun sends from it.
Should I add yourapp.com or mg.yourapp.com?
Add yourapp.com, the brand domain in your From address. Mailgun gives each domain, subdomains included, its own DKIM authority, and mg.yourapp.com stays with Mailgun as the domain it sends on. Mailbox providers score the domain in your From address, so the reputation built here counts for every Mailgun send from yourapp.com.
Can I see whether it is working?
Yes. Inbox placement tests show where your Mailgun mail lands, inbox or Spam, across the major mailbox providers, and blacklist monitoring keeps watching the domain afterwards.
About the Mailgun facts on this page

Checked against Mailgun's own documentation on 12 October 2026. Mailgun is a trademark of its owner; SenderSignal is not affiliated with it.

Other transactional & smtp: Amazon SES, Postmark, SparkPost, Resend, Mailjet. All use cases.

Mailgun keeps sending

Warm the domain behind your Mailgun mail.

Start free, add your brand domain, and keep every API call going to Mailgun while its reputation builds.

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