Switch from Mailgun to Anypost

What's the same, what changed

Both platforms send authenticated email, report delivery events, and support domain-based sender identity. The differences are mostly in the wire format: how you authenticate and how you shape the request body.

Five steps to switch

You can run Mailgun and Anypost in parallel during cutover; they are fully independent. Migrate one email type at a time and verify delivery before cutting over completely.

curl --user 'api:YOUR_KEY' \
  https://api.mailgun.net/v3/mg.example.com/messages \
  -F from='[email protected]' \
  -F to='[email protected]' \
  -F subject='Hello' \
  -F html='<p>Hi there.</p>'

curl https://api.anypost.com/v1/email \
  -H 'Authorization: Bearer ap_…' \
  -H 'Content-Type: application/json' \
  -d '{
    "from": "[email protected]",
    "to": ["[email protected]"],
    "subject": "Hello",
    "html": "<p>Hi there.</p>"
  }'

The same change in every SDK

The pattern is consistent: remove the Basic auth setup, remove the domain from the URL, switch from form fields to JSON keys. Pick your language.

curl --user 'api:YOUR_KEY' \
  https://api.mailgun.net/v3/mg.example.com/messages \
  -F from='Acme <[email protected]>' \
  -F to='[email protected]' \
  -F subject='Welcome' \
  --form-string html='<p>Glad you are here.</p>'

curl https://api.anypost.com/v1/email \
  -H 'Authorization: Bearer ap_…' \
  -H 'Content-Type: application/json' \
  -d '{
    "from": "Acme <[email protected]>",
    "to": ["[email protected]"],
    "subject": "Welcome",
    "html": "<p>Glad you are here.</p>"
  }'

Event names changed, lifecycle didn't

Mailgun uses a flat event string with a severity sub-field. Anypost namespaces events under email.* and gives permanent and temporary failures their own event types.

Anypost also emits email.suppressed when a send is dropped because the address is already on your suppression list. There's no Mailgun equivalent, and you don't need to handle it to migrate.

// Before (Mailgun event names)
switch (payload["event-data"].event) {
  case "delivered":
    markDelivered(payload["event-data"].message.headers["message-id"]);
    break;
  case "failed":
    if (payload["event-data"].severity === "permanent")
      suppressAddress(payload["event-data"].recipient);
    break;
  case "complained": unsubscribe(payload["event-data"].recipient); break;
  case "opened":     recordOpen(payload["event-data"]); break;
  case "clicked":    recordClick(payload["event-data"].url); break;
}
 
// After (Anypost event names; events arrive in a batched array)
for (const event of req.body.events) {
  switch (event.type) {
    case "email.delivered":  markDelivered(event.data.email_id); break;
    case "email.bounced":    suppressAddress(event.data.recipient); break;
    case "email.delayed":    scheduleRetryNotice(event.data.email_id); break;
    case "email.complained": unsubscribe(event.data.recipient); break;
    case "email.opened":     recordOpen(event.data); break;
    case "email.clicked":    recordClick(event.data.tracking.url); break;
  }
}

Using SMTP instead of the API?

Mailgun uses per-domain SMTP credentials, a separate username and password for each domain, managed in the dashboard. Anypost uses a single API key as the password across all your domains.

SMTP_HOST=smtp.mailgun.org
SMTP_PORT=587
SMTP_USER[email protected]
SMTP_PASS=<domain-smtp-password>
SMTP_TLS=true

SMTP_HOST=smtp.anypost.com
SMTP_PORT=587
SMTP_USER=anypost
SMTP_PASS=ap_…
SMTP_TLS=true

Anypost supports ports 587 (recommended), 2587, and 25. STARTTLS is required on every port, and there is no implicit-TLS port, so if your current Mailgun config uses port 465, switch to 587. See Sending over SMTP.