SMTP 550 Error Fix

Swift_TransportException: Expected response code 250 but got code "550", with message "550 5.7.1 Unconfigured Sending Domain"

means that **your SMTP server rejected the email** because the domain you are trying to send **from** has not been properly configured for sending emails through that server.

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### 🔍 **Understanding the Error**
– **550 5.7.1** is a common SMTP error for rejection due to security or policy.
– **"Unconfigured Sending Domain"** means that your SMTP provider (like SendGrid, Mailgun, Amazon SES, etc.) is blocking the message because **your sending domain hasn't been verified/configured** in their system.

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### ✅ **Steps to Resolve**

1. **Check your "From" address in SwiftMailer**:

$message->setFrom('noreply@yourdomain.com', 'Your Name');

– Ensure `yourdomain.com` is **correctly configured with your SMTP provider**.

2. **Login to your SMTP provider** (e.g., Mailgun, SendGrid, SES, etc.)
– Go to **"Sending Domains"** or **"Verified Domains"**
– Ensure that the domain `yourdomain.com`:
– Is **added**
– Has **DNS records configured** (SPF, DKIM, possibly DMARC)
– Is **verified**

3. **Add and verify the domain if missing**:
– You'll usually be given TXT and CNAME records to add to your DNS.
– After DNS propagates (~5 minutes to a few hours), your domain will be verified.

4. **Use a verified domain or a known sending address temporarily**:
– Try sending from a default email like `test@yourverifieddomain.com` to see if it works.

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### 🛠 Optional Debugging Tip
You can **log the full SMTP interaction** by enabling SwiftMailer debug output:

$transport->setLogger(new Swift_Plugins_Loggers_EchoLogger());
$mailer->registerPlugin(new Swift_Plugins_LoggerPlugin($transport->getLogger()));

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Let me know which SMTP provider you're using (e.g., Gmail, SendGrid, Mailgun, SES), and I can give you exact DNS records or setup steps.