Summary
The SMTP error 550 5.5.5 indicates a permanent email delivery failure primarily due to policy rejections, spam filtering, or sender reputation issues on the recipient's mail server. While senders can verify recipient addresses, ensure proper authentication (SPF, DKIM), check their sender reputation, maintain clean email lists, and review sending practices, the resolution typically requires action from the recipient's side, such as configuring their server to accept mail, properly implement whitelisting, or adjust spam filtering rules.
Key findings
- Permanent Failure: Error 550 5.5.5 signifies a hard bounce and a permanent failure in email delivery.
- Policy Rejection: The error often stems from policy restrictions, spam filters, or content filters implemented on the recipient's server.
- Recipient-Side Issue: The problem primarily lies with the recipient's server configuration or the recipient's email address itself.
- Sender Reputation Matters: A poor sender reputation or blacklisted IP address can trigger this error.
- Whitelisting Inconsistencies: Even when whitelisting is claimed, it might not be correctly implemented or effective.
Key considerations
- Verify Recipient Address: Double-check the recipient's email address for any typos or inaccuracies.
- Check Sender Reputation: Use online tools and services to assess your sender reputation and identify potential blacklisting issues.
- Implement Authentication: Ensure that SPF and DKIM records are properly configured for your sending domain to improve deliverability.
- Contact Recipient: Reach out to the recipient through alternative channels (phone, other email) to request whitelisting and confirm their email settings.
- Maintain List Hygiene: Regularly clean your email list to remove invalid, inactive, or problematic addresses.
- Review Sending Practices: Analyze sending practices to adhere to best practices and avoid being flagged as spam.
- Address Envelope From: If the rejection happens before DATA command, ensure the Envelope From address is correctly whitelisted.
- Analyze Server Logs: Examine server logs on both sending and receiving ends to gain deeper insights into the root cause.
- Inform Recipient IT: If the issue persists, encourage the recipient to contact their IT support for further investigation and resolution.
What email marketers say
9 marketer opinions
SMTP error 550 5.5.5 indicates a permanent rejection of an email due to policy restrictions, spam filtering, or sender reputation issues on the recipient's server. Common solutions involve verifying the recipient's email address, checking sender reputation and authentication (SPF, DKIM), ensuring the IP isn't blacklisted, contacting the recipient to request whitelisting, and maintaining good email list hygiene.
Key opinions
- Permanent Rejection: Error 550 5.5.5 signifies a permanent failure in email delivery, meaning the email will not reach the recipient.
- Policy Restrictions: The error often stems from the recipient's server policies, such as spam filters or sender restrictions.
- Sender Reputation: A poor sender reputation or blacklisted IP address can trigger this error.
- Recipient-Side Issue: The problem usually resides on the recipient's server configuration, not the sender's.
Key considerations
- Verify Recipient Address: Ensure the recipient's email address is correct and free of typos.
- Check Sender Reputation: Use online tools to assess your sender reputation and identify potential blacklisting.
- Authentication: Confirm that SPF and DKIM records are properly configured for your sending domain.
- Contact Recipient: Reach out to the recipient through alternative channels to request whitelisting.
- List Hygiene: Regularly clean your email list to remove invalid or inactive addresses.
- Review Sending Practices: Warm up IP address and review your sending practices to ensure you are following best practices
Marketer view
Email marketer from SendPulse suggests checking the recipient's email address for typos and ensuring the sender's IP address isn't blacklisted. They also recommend contacting the recipient through another channel to confirm their email settings and request whitelisting.
21 Jul 2022 - SendPulse
Marketer view
Email marketer from Mailjet shares that a 550 error is a permanent rejection of the email. It often means the email address doesn't exist or the recipient's server is blocking the sender. The error `550 5.5.5` specifically indicates issues with policy restrictions.
13 Oct 2021 - Mailjet
What the experts say
5 expert opinions
SMTP error 550 5.5.5 indicates a permanent email delivery failure, often due to the recipient's server policies, spam filtering, or whitelisting issues. Resolution typically requires action from the recipient's side, such as configuring their server to accept mail from the sender or properly implementing whitelisting. Senders should also maintain clean email lists to prevent further issues.
Key opinions
- Permanent Error: 5xx errors, including 550 5.5.5, are hard bounces indicating permanent failures.
- Recipient-Side Fix: The primary fix lies with the recipient's server configuration, often requiring whitelisting or policy adjustments.
- Whitelisting Issues: Claims of whitelisting may be ineffective if not implemented correctly on the recipient's end.
- Policy or Spam Filtering: The recipient's server may be rejecting the email due to established policies or spam filtering rules.
Key considerations
- Contact Recipient's IT: Advise the recipient to have their IT department review server settings and allow emails from the sender.
- Envelope From: If rejection occurs before DATA, ensure the Envelope From address is whitelisted.
- List Cleaning: Regularly clean email lists to remove invalid addresses and prevent future bounces.
- Verify Whitelisting: Double-check with the recipient that whitelisting is correctly implemented on their server.
Expert view
Expert from Email Geeks shares that the fix is on the recipient's end and the sender cannot fix it from the outside. They should tell the recipient IT to resolve the issue.
28 Apr 2023 - Email Geeks
Expert view
Expert from Email Geeks shares that in this kind of scenario, it's common for the client or client IT to say "oh, we've whitelisted it, you should be fine now!" The bounces you are seeing show that the whitelisting is not working or not implemented properly.
23 Jul 2024 - Email Geeks
What the documentation says
5 technical articles
SMTP error 550 5.5.5 signifies a permanent delivery failure due to a policy rejection on the recipient's mail server. This rejection often stems from spam filtering rules, sender reputation issues, or syntax/protocol errors. The recipient's server operator deliberately chooses not to deliver the mail, meaning the resolution is primarily on the receiving end.
Key findings
- Policy Rejection: The primary cause is a policy rejection on the recipient's mail server.
- Permanent Failure: 5xx errors indicate permanent failures, rendering the email undeliverable.
- Syntax/Protocol Errors: 5.5.x codes often relate to syntax or protocol errors preventing command execution.
- Recipient-Side Issue: The issue is primarily with the receiving server's configuration and policies.
Key considerations
- Contact Recipient's Admin: Communicate with the recipient's server administrator to understand the specific policy causing the rejection.
- Check Sender Reputation: Monitor and maintain a good sender reputation to avoid being flagged by recipient servers.
- Verify Email Syntax: Ensure the email adheres to proper syntax and protocol standards to prevent errors.
- Review Server Logs: Analyze server logs for more detailed information about the rejection reason.
Technical article
Documentation from Microsoft Support explains that error 550 5.5.5 indicates a policy rejection. This means the recipient's mail server has policies in place that prevent the message from being delivered, often related to spam filtering or sender reputation.
24 Mar 2022 - Microsoft Support
Technical article
Documentation from Exim Wiki indicates a 550 error generally means a permanent failure on the receiving server. The specific code 5.5.5 can be tailored by the admin of the remote server, but the general meaning implies that the remote server operator is making a deliberate choice to not deliver your mail.
8 Jan 2023 - Exim Wiki
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