Summary
A `550 5.7.1` error generally signifies a permanent delivery failure and is often treated as a hard bounce, typically related to security policies, delivery restrictions, or sender reputation issues. However, Vade's specific implementation is a concern because they use this code broadly, requiring users to check their webpage for clarification. Experts emphasize checking the full error message or SMTP response from the receiving server, as the specific reason for the rejection depends on the server's configuration. Some services treat `5.7.1` strictly as a hard bounce with automatic address suppression, and the SMTP code is highly variable and you should check all the responses to see why it failed.
Key findings
- Hard Bounce Indicator: `550 5.7.1` usually indicates a hard bounce and permanent delivery failure.
- Security/Policy Related: The error is often due to security policies, recipient server restrictions, or sender reputation problems.
- Vade's Non-Standard Use: Vade's broad use of `550 5.7.1` is non-standard, necessitating checking their webpage for details.
- Implementation Matters: The exact meaning of `5.7.1` can vary depending on the mail server and service.
- SMTP Responses provide clarity: You should check the full message or SMTP Response for clarity and reasons why it failed
Key considerations
- Check Full Message: Always examine the complete error message/SMTP Response from the receiving server to understand the specific rejection reason.
- Investigate Restrictions: For Exchange Server, investigate sending limits and permissions if encountering `5.7.1` NDRs.
- Bounce Handling Procedures: Follow recommended bounce handling procedures for the specific service (e.g., suppression in Amazon SES).
- Double check: Double check all the responses as the code itself is highly variable.
What email marketers say
9 marketer opinions
The consensus is that a `550 5.7.1` error generally indicates a hard bounce due to permanent delivery failure, often related to security policies or sender reputation issues. However, several sources emphasize the importance of examining the full error message from the receiving server for a precise understanding of the rejection reason, as the code itself can be used for various specific issues. Some also state it's crucial to look at the text portion of the SMTP response for clarity.
Key opinions
- Hard Bounce Indicator: `550 5.7.1` typically signals a hard bounce, implying a permanent delivery failure.
- Security/Policy Related: The error often stems from security policies, recipient server restrictions, or sender reputation problems.
- SMTP Response Clarity: It's important to look at the text portion of the SMTP response for clarity.
- 5xx codes indicate an error: 5xx codes are always a delivery error and treated as a hard bounce
Key considerations
- Detailed Error Message: Always check the complete error message from the receiving server for the specific reason behind the bounce.
- Policy Verification: Investigate the specific policies or security measures causing the rejection before automatically categorizing it as a hard bounce.
- Diagnostic Code: Look at the full diagnostic code to check the original failure reason in the bounce messages.
Marketer view
Email marketer from MailerQ explains that although `5.7.1` often indicates an issue with anti-spam policies it's still worth checking what policies are in place before automatically classing as a hard bounce
27 Jul 2022 - MailerQ
Marketer view
Email marketer from Mailjet shares that a `5.7.1` error usually indicates a permanent failure and should be treated as a hard bounce. They suggest reviewing your sending practices to prevent such errors.
6 Apr 2025 - Mailjet
What the experts say
6 expert opinions
Experts agree that while a `550 5.7.1` error indicates a permanent delivery failure, Vade's specific implementation raises concerns. Vade uses this code broadly, making it difficult to discern the exact cause without consulting their webpage. This deviates from SMTP standards, where different codes should signify distinct failures (e.g., `550 5.1.1` for "user unknown"). The actual reason for the rejection depends on the receiving server's configuration and should be reviewed in the returned message.
Key opinions
- Vade's Internal Code: `_403` is Vade's internal code for `550 5.7.1`, but their documentation URL is incorrect.
- Non-Standard Use: Vade's use of `550 5.7.1` for multiple rejection types is non-standard and problematic.
- Delivery Policy/Security: The `550 5.7.1` error usually indicates a delivery policy violation or security restriction.
- Error Code Variability: The specific cause of a `550 5.7.1` error is highly variable and depends on the receiving server.
Key considerations
- Check Full Message: Review the specific message returned with the error code to understand the exact reason for the failure.
- Potential Misinterpretation: Be aware that Vade's broad use of `550 5.7.1` may lead to misinterpretations without additional investigation.
- ESP is wrong: The ESP is wrong if it blames Vade for the SMTP error code itself, as the 403 isn't an SMTP error code. The first 3 digits in an error message is the error code.
Expert view
Expert from Email Geeks explains that `_403` is Vade's internal code for `550 5.7.1` and points out that their site's URL is incorrect.
28 Jul 2023 - Email Geeks
Expert view
Expert from Word to the Wise notes that the `550 5.7.1` status code is highly variable. While the first number indicates it's a permanent error, the specific cause depends on the receiving server's configuration. The best course of action is to review the specific message returned along with the error code.
13 Jan 2023 - Word to the Wise
What the documentation says
4 technical articles
Documentation sources indicate that a `550 5.7.1` error, as defined by SMTP enhanced status codes, generally signifies a permanent delivery failure due to security or policy rejections. While the standard provides a framework, specific implementations can vary, with some services like Amazon SES treating it definitively as a hard bounce and automatically suppressing affected addresses. Microsoft Exchange Server interprets it as a delivery restriction or policy issue, suggesting investigation into sending limits and permissions.
Key findings
- Permanent Failure: `5.7.1` signals a permanent delivery failure.
- Security/Policy Rejection: The error usually stems from security policies or delivery restrictions.
- Implementation Variation: The specific meaning can vary depending on the mail server implementation.
- Hard Bounce Treatment: Some services, like Amazon SES, treat it strictly as a hard bounce with automatic suppression.
Key considerations
- Investigate Restrictions: If using Microsoft Exchange, investigate sending limits and permissions to resolve the issue.
- Sender Reputation: Be aware that repeated `5.7.1` errors can negatively impact sender reputation.
- Bounce Handling: Handle `5.7.1` bounces according to the specific service's recommendations (e.g., suppression in Amazon SES).
Technical article
Documentation from Microsoft explains that in Exchange Server, a `5.7.1` NDR (Non-Delivery Report) often indicates a delivery restriction or security policy preventing the email from reaching the recipient. It suggests that the sender should investigate sending limits and permissions.
5 Dec 2024 - Microsoft
Technical article
Documentation from IETF explains that SMTP enhanced status codes, including the `5.7.1` code, provide a standardized way to indicate permanent delivery failures related to security or policy rejection. However, the specific meaning can vary by implementation.
20 Jan 2023 - IETF
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