SMTP error 550 indicates your email was permanently rejected (5xx) and couldn't reach the recipient's address. This often signifies the recipient's email is non-existent, the domain has issues, or the message violates server policies (phpmailer, jenkins).

What are the cases covered in SMTP Error 550?

Common scenarios triggering SMTP Error 550:

1. Nonexistent Recipient: The recipient's email address ("RCPT TO" or "To:") is invalid and doesn't correspond to a real account or mailbox (phpmailer, jenkins).
2. Invalid Recipient Domain: The recipient's email domain (e.g., example.com) is non-existent, expired, or has DNS (Domain Name System) problems.
3. Policy Violations: The email content violates server policies, such as containing spam, malware, or exceeding size limits.
4. Blacklisting: The sender's domain or IP address is blacklisted, causing email rejection.

What’s Causing This SMTP Error 550 In Your Servers?

Potential causes of SMTP Error 550:

• Incorrect Recipient Address: Double-check that the recipient's email address is accurate, complete, and corresponds to a valid account or mailbox (phpmailer, jenkins).
• Recipient Domain Issues: Verify that the recipient's email domain is functioning correctly, has no DNS issues, and isn't expired.
• Review Email Content: Analyze the email for potential policy violations like spammy content, excessive attachments, or malicious links.
• Remove from Blacklists: If your sender's domain or IP is blacklisted, take steps to get removed and improve your email reputation.

How to Resolve SMTP Error 550 - Step-by-Step Solution

1. Verify Recipient Address: Ensure the recipient's email address is accurate, complete, and belongs to a valid account or mailbox (phpmailer, jenkins).
2. Check Recipient Domain: Confirm that the recipient's email domain is functioning correctly, has no DNS issues, and isn't expired.
3. Revise Email Content: Address any potential policy violations in the email message, such as removing spammy content or harmful attachments, to comply with the recipient server's policies.
4. Request Blacklist Removal: If your sender's domain or IP is blacklisted, request removal from the relevant blacklists and implement measures to improve your email sending practices.

SMTP Error 550 Examples

• "550 5.1.1 recipient@example.com: Recipient address does not exist."
• "550 5.4.5 recipient@example.com: Domain name not found. Check recipient domain."
• "550 5.7.0 Message blocked due to policy violations. Content flagged as spam."
• "550 5.7.1 sender@example.com: Sender's domain blacklisted for abusive behavior."

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