Migrate from Mailgun to turboSMTP: SMTP and API Guide

Switching from Mailgun to turboSMTP comes down to two changes: new SMTP credentials, or converting Mailgun’s form-data messages endpoint to turboSMTP’s JSON API. This guide walks through both, along with DNS, suppressions, webhooks, and a safe cutover. Mailgun EU-region users can move straight to turboSMTP’s EU hosts.

Mailgun settings checked on 27 October 2026 against its API overview, SMTP guide, and send reference. Confirm current plan requirements before cutover.

Before you start

Create a turboSMTP account

Authenticate your sending domain

Merge turboSMTP’s SPF include into your existing single SPF record and add its DKIM record. Keep Mailgun authorized until cutover and queued delivery are complete. See SPF, DKIM, and DMARC.

Export your suppressions

Export bounces, unsubscribes, and complaints from Mailgun and import them with POST /suppressions/import. Review domain and list-specific opt-outs before mapping them to account suppressions. See the Suppressions API.

Option 1: Switch SMTP credentials

Setting	Mailgun	turboSMTP
Host	`smtp.mailgun.org` (EU: `smtp.eu.mailgun.org`)	`pro.turbo-smtp.com` (EU: `pro.eu.turbo-smtp.com`)
Port and encryption	587 with STARTTLS	587 or 2525 with STARTTLS; 465 or 25025 with implicit TLS; 25 also available
Username	Your per-domain SMTP user	Your turboSMTP Consumer Key
Password	Your per-domain SMTP password	Your turboSMTP Consumer Secret

SMTP_HOST=smtp.mailgun.org
SMTP_PORT=587
SMTP_USER=postmaster@YOUR_DOMAIN_NAME
SMTP_PASS=YOUR_MAILGUN_SMTP_PASSWORD

SMTP_HOST=pro.eu.turbo-smtp.com
SMTP_PORT=587
SMTP_USER=YOUR_CONSUMER_KEY
SMTP_PASS=YOUR_CONSUMER_SECRET

SMTP_HOST=smtp.mailgun.org
SMTP_HOST=pro.eu.turbo-smtp.com
SMTP_PORT=587
SMTP_USER=postmaster@YOUR_DOMAIN_NAME
SMTP_USER=YOUR_CONSUMER_KEY
SMTP_PASS=YOUR_MAILGUN_SMTP_PASSWORD
SMTP_PASS=YOUR_CONSUMER_SECRET

Configure your client to require STARTTLS for these port 587 examples. Global and EU support the same ports and TLS modes. Enable SMTP Sending on your key and check any IP restrictions. See SMTP Setup.

Remove any X-Mailgun-* headers (for example X-Mailgun-Tag or X-Mailgun-Variables) from your messages. They have no effect on turboSMTP.

Option 2: Convert API calls

Mailgun sends form fields to a per-domain URL with Basic auth. turboSMTP takes a JSON body on a single endpoint with header authentication. Enable HTTP API Sending on the Consumer Key used below. 1. Replace Basic auth and form fields with headers and a JSON body:

curl -s --user 'api:YOUR_API_KEY' \
  https://api.eu.mailgun.net/v3/YOUR_DOMAIN_NAME/messages \
  -F from='Shop <orders@yourdomain.com>' \
  -F to='recipient-1@example.com' \
  -F to='recipient-2@example.com' \
  -F subject='Your order has shipped' \
  -F text='Your order is on its way.' \
  --form-string html='<p>Your order is on its way.</p>'

curl -X POST https://api.eu.turbo-smtp.com/api/v2/mail/send \
  -H "consumerKey: YOUR_CONSUMER_KEY" \
  -H "consumerSecret: YOUR_CONSUMER_SECRET" \
  -H "Content-Type: application/json" \
  -d @payload.json

curl -s --user 'api:YOUR_API_KEY' \ # [!code --:8]
  https://api.eu.mailgun.net/v3/YOUR_DOMAIN_NAME/messages \
  -F from='Shop <orders@yourdomain.com>' \
  -F to='recipient-1@example.com' \
  -F to='recipient-2@example.com' \
  -F subject='Your order has shipped' \
  -F text='Your order is on its way.' \
  --form-string html='<p>Your order is on its way.</p>'
curl -X POST https://api.eu.turbo-smtp.com/api/v2/mail/send \ # [!code ++:5]
  -H "consumerKey: YOUR_CONSUMER_KEY" \
  -H "consumerSecret: YOUR_CONSUMER_SECRET" \
  -H "Content-Type: application/json" \
  -d @payload.json

2. Move the form fields into the JSON payload:

payload.json

{
  "from": "Shop <orders@yourdomain.com>",
  "to": "recipient-1@example.com,recipient-2@example.com",
  "subject": "Your order has shipped",
  "content": "Your order is on its way.",
  "html_content": "<p>Your order is on its way.</p>"
}

Field mapping

Mailgun	turboSMTP	Notes
`--user 'api:KEY'`	`consumerKey` + `consumerSecret` headers	`Authorization` is ignored by `/mail/send`; it cannot authenticate the request
`/v3/{domain}/messages`	`/api/v2/mail/send`	One endpoint for all domains
`from`	`from`	Address, optionally `Name <address>`
`to` (repeated)	`to`	Comma-separated string
`cc` / `bcc`	`cc` / `bcc`	Comma-separated strings
`text`	`content`	Plain text body
`html`	`html_content`	HTML body
`attachment` (file upload)	`attachments[]`	Base64 `content`, `name`, `type`. See Attachments
`h:X-Custom-Header`	`custom_headers`	Object of header names and values
`v:my-var`	No direct equivalent for a metadata map	Store metadata in your application; use a UUID `reference_id` for correlation
`o:tag`	`X-campaign-ID`	Review how your application groups messages; these are not identical features
`inline`	`attachments[]` with `content_id`	Use a bare `content_id` such as `logo`; reference it in HTML as `cid:logo@<sender-domain>`. See inline images
`/messages.mime`	SMTP relay	`/mail/send` does not use `mime_raw`; send pre-built MIME over SMTP with your Consumer Key and Secret

Replace webhooks

Configure turboSMTP webhooks and map Mailgun events to turboSMTP’s delivery events (PROCESSED, DROPPED, DELIVERED, DEFERRED, BOUNCED) and engagement events (OPENED, CLICKED, UNSUBSCRIBED, REPORT). turboSMTP webhooks are unsigned. Replace any Mailgun signature check with endpoint protection appropriate for turboSMTP, such as HTTP Basic authentication. Check enabled events and plan availability under Settings → Notifications → Webhooks → Edit. Free and Basic include a 30-day webhook demo; settings changes can take up to one hour.

Cut over safely

Send a test

Send to an internal address and confirm SPF and DKIM pass.

Ramp up gradually

Route part of your traffic to turboSMTP and compare results in the statistics dashboard.

Switch fully and clean up DNS

Move all traffic and sync new opt-outs. After Mailgun’s queue has drained, remove only the DNS records and SPF mechanisms no longer needed by another service.

Frequently asked questions

I use Mailgun's EU region. Which turboSMTP host should I use?

Use api.eu.turbo-smtp.com for API sending and pro.eu.turbo-smtp.com for SMTP. Review regional setup and processing terms for your requirements.

Do I need separate credentials per domain like Mailgun?

No. One Consumer Key and Consumer Secret pair works for all your authenticated domains. Use subaccounts if you need to separate clients or projects.

Can turboSMTP help me migrate?

Contact support to discuss your migration. Available support channels depend on your plan.

Comparisons

Migration Guides

Migrate from Mailgun to turboSMTP: SMTP and API Guide

Before you start

Option 1: Switch SMTP credentials

Option 2: Convert API calls

Field mapping

Replace webhooks

Cut over safely

Frequently asked questions

​Before you start

​Option 1: Switch SMTP credentials

​Option 2: Convert API calls

​Field mapping

​Replace webhooks

​Cut over safely

​Frequently asked questions

Before you start

Option 1: Switch SMTP credentials

Option 2: Convert API calls

Field mapping

Replace webhooks

Cut over safely

Frequently asked questions