Mailgun splits its infrastructure between US and EU regions for GDPR/data-residency. The two have completely separate dashboards, separate SMTP hosts, and separate credentials. Pick the region when you create the account - you cannot change it later.
Find your SMTP credentials
- Sign in to
app.mailgun.com(US) orapp.eu.mailgun.com(EU). - Left nav, Send → Sending → Domains.
- Click your verified sending domain (e.g.
mail.yourbiz.com). - Top tabs, click Domain settings.
- Click the SMTP credentials tab.
- You will see the auto-created
postmaster@your-domainuser. To use it, click Reset Password (Mailgun does not display the existing password, so a reset is required to get one you can paste). - Copy the new password immediately - it shows once.
Create a dedicated SMTP user (recommended)
Instead of reusing the master postmaster credential across multiple services, create a dedicated user per integration so a leak in one place does not compromise all sends.
- Same SMTP credentials tab.
- Click New SMTP user.
- Set login name (e.g.
inflowave@your-domain). - Mailgun generates a password automatically. Copy it once.
Connect to Inflowave
- Inflowave → Settings → Email → Add sending domain → Custom SMTP.
- Host:
smtp.mailgun.org(US) orsmtp.eu.mailgun.org(EU). - Port:
587. - Username:
postmaster@your-sending-domain(or your dedicated SMTP user). - Password: the SMTP password from the credentials tab.
- Save, send a test.
Troubleshooting
Wrong region (US credentials on EU host or vice versa), or stale password. Click Reset Password on the SMTP credentials tab and paste fresh.
You are sending from a sandbox domain to a recipient who is not on your verified recipient list. Sandbox can only send to 5 authorized recipients. Add a real verified domain.
EU and US accounts give different DNS records. Make sure you copied from the same regional dashboard that holds your account.
Sandbox and free-tier limits
- Sandbox domain (the
sandboxXXX.mailgun.orgdomain Mailgun gives you on signup): can only send to 5 authorized recipients you explicitly verify, total. For testing the integration, not production. - Foundation plan (free): 100 emails/day to verified recipients only - useful only for testing.
- Region matters for DNS: The SPF, DKIM, MX, and tracking CNAME records differ between US and EU. Paste the records from the region your account is in.
- Production volume requires the Flex plan or above - pay-as-you-go pricing kicks in.
