This is the core of the Transactional API: POST /messages/send. Everything else we've covered is just management around this one call. Pass it a recipient, subject, body and sender, and it delivers the email.
from_email has to
be on a domain you've verified in Mandrill (Settings → Sending Domains) with
SPF + DKIM records published. Unverified = instant rejection. See
Setup, step 5 if you haven't done this yet.
' . h($_POST['to_email']) . ' to ALLOWED_TEST_RECIPIENTS '
. 'in config.php, or clear that list to allow any recipient.';
require 'footer.php';
exit;
}
// --- Build the message object ----------------------------
// The entire email is described by a single "message" array
// passed inside the params. Mandrill accepts a LOT of optional
// fields here (tracking, tags, metadata, attachments, merge vars) —
// this demo uses the minimum required for a well-formed send.
$message = [
'from_email' => trim($_POST['from_email']),
'from_name' => trim($_POST['from_name']),
'subject' => trim($_POST['subject']),
'html' => $_POST['html'],
'text' => $_POST['text'],
'to' => [
[
'email' => trim($_POST['to_email']),
'name' => trim($_POST['to_name']),
'type' => 'to', // 'to', 'cc' or 'bcc'
],
],
// Recommended defaults:
'track_opens' => true,
'track_clicks' => true,
'tags' => ['demo-send'], // shows up in your stats
];
$result = mandrill_call('/messages/send', ['message' => $message]);
// ---------------------------------------------------------
if (!mandrill_is_error($result) && is_array($result['decoded'])) {
foreach ($result['decoded'] as $recipient) {
$status = $recipient['status'] ?? 'unknown';
$class = ($status === 'sent' || $status === 'queued') ? 'ok' : 'warn';
echo '$result = mandrill_call('/messages/send', [
'message' => [
'from_email' => 'noreply@yourdomain.com',
'from_name' => 'Your Company',
'subject' => 'Welcome!',
'html' => '<h1>Hi</h1>',
'text' => 'Hi',
'to' => [
['email' => 'user@example.com', 'name' => 'User', 'type' => 'to'],
],
'track_opens' => true,
'track_clicks' => true,
'tags' => ['welcome-email'],
],
]);Unlike the other endpoints, /messages/send returns an array — one entry per recipient:
[
{
"email": "user@example.com",
"status": "sent",
"reject_reason": null,
"_id": "abc123..."
}
]Possible status values:
| Status | Meaning |
|---|---|
sent | Accepted and delivered to the receiving mailserver. |
queued | Accepted, will be delivered shortly. |
scheduled | Held for a scheduled send time. |
rejected | Mandrill refused to send — see reject_reason. |
invalid | Malformed address or similar. |
Common reject_reason values you'll hit in testing:
unsigned — the from_email domain isn't verified.hard-bounce — recipient is on your denylist from a prior bounce.spam — recipient previously complained. Allowlist the address (Step 3) to override.unsub — recipient unsubscribed.You'll want these in production:
'message' => [
// ...required fields...
// Group related sends so you can see aggregate stats by category
'tags' => ['password-reset', 'customer-type:premium'],
// Attach your own IDs for webhook correlation
'metadata' => ['website_order_id' => 'ORD-12345'],
// Merge fields — per-recipient variables
'merge_vars' => [[
'rcpt' => 'user@example.com',
'vars' => [
['name' => 'FIRSTNAME', 'content' => 'Jane'],
],
]],
// Reply-To header
'headers' => ['Reply-To' => 'support@yourdomain.com'],
// Don't let Mandrill auto-append your opens pixel / click redirects
'track_opens' => false,
'track_clicks' => false,
]