Summary
Gmail accounts bounce with 'No Such User' errors due to a combination of factors. These include temporary Gmail-specific issues, mistyped or non-existent email addresses, suspended or deleted accounts (including aliases), incorrect domain MX records, temporary server issues, inaccurate email verification services, and poor email list hygiene. A surge in these bounces was noted around December 2020. Proper list hygiene, MX record configuration, and validating email addresses are essential to mitigate these issues.
Key findings
- Address Validity: The primary reason for 'No Such User' errors is that the email address is invalid or doesn't exist on the mail server.
- Typographical Errors: Simple typos in the email address are a significant cause, often missed even by validation services.
- Account Status: The recipient's account might be suspended, deleted, or inactive.
- MX Record Configuration: Incorrectly set up MX records prevent proper email delivery to the domain.
- Gmail Issues: Temporary server issues or broader Gmail outages can cause valid addresses to bounce.
- List Hygiene: Outdated and poorly maintained email lists contribute significantly to bounce rates.
- Verification Inaccuracies: Email verification services can sometimes incorrectly flag valid addresses as invalid.
Key considerations
- Validate Addresses: Always double-check email addresses for typos or inaccuracies.
- Monitor Gmail Status: Stay informed about potential Gmail outages or server issues.
- Check Account Status: If possible, confirm the recipient's account is active and valid.
- Verify MX Records: Ensure MX records for your domain are correctly configured.
- Clean Email Lists: Regularly remove inactive or invalid addresses from your email lists.
- Evaluate Verification Services: Assess the accuracy of your email verification service and consider alternatives if necessary.
- Resend After Delay: If a temporary server issue is suspected, try resending the email later.
What email marketers say
21 marketer opinions
Gmail accounts bounce with 'No Such User' errors due to various reasons including: temporary Gmail issues, mistyped or non-existent email addresses, suspended accounts, incorrect domain MX records, deleted accounts (including aliases), temporary server issues, email verification services incorrectly marking addresses as invalid, or poor email list hygiene. Early December 2020 saw a spike in these issues. Checking for typos, verifying MX records, and maintaining clean email lists are recommended.
Key opinions
- Gmail Issues: Temporary issues on Gmail's end can trigger 'No Such User' errors, particularly noted in early December 2020.
- Typographical Errors: Mistyped email addresses are a common cause.
- Account Status: The recipient's account may be deleted, suspended, or simply not exist.
- MX Record Configuration: Incorrectly configured MX records for the domain can lead to delivery failures.
- List Hygiene: Poor email list hygiene, including outdated or inactive addresses, contributes to bounces.
- Verification Service Errors: Third-party email verification services might incorrectly mark valid addresses as invalid.
Key considerations
- Double-Check Addresses: Always verify the recipient's email address for typos or errors.
- Monitor Gmail Status: Be aware of potential widespread Gmail issues that may cause temporary bounces.
- Review Account Status: If possible, confirm with the recipient that their account is active and valid.
- Verify MX Records: Ensure the domain's MX records are correctly configured to point to Gmail.
- Maintain List Hygiene: Regularly clean your email lists to remove inactive and invalid addresses.
- Review Verification Practices: Evaluate the accuracy and reliability of any email verification services used.
- Resend After Delay: If a temporary server issue is suspected, try resending the email after a short delay.
Marketer view
Email marketer from Email Geeks shares experiencing a sudden deliverability hit.
15 Mar 2025 - Email Geeks
Marketer view
Email marketer from Email Geeks shares an email sent from personal Gmail account to another Gmail account bounced with "550 5.1.1 The email account that you tried to reach does not exist."
3 Jul 2022 - Email Geeks
What the experts say
2 expert opinions
Gmail accounts bounce with 'No Such User' errors primarily because the email address doesn't exist on the mail server. This can result from typos, closed accounts, or misconfigured domain settings. Maintaining good list hygiene, which includes regularly cleaning email lists and verifying domain records, is crucial to prevent these bounces.
Key opinions
- Non-Existent User: 'No Such User' errors indicate the email address is not valid on the receiving mail server.
- Possible Causes: Typographical errors, closed accounts, and improper domain configuration are common reasons.
- List Hygiene Importance: Maintaining a clean and up-to-date email list significantly reduces 'No Such User' bounces.
Key considerations
- Address Verification: Double-check email addresses for any typos before sending.
- List Maintenance: Regularly remove inactive or invalid email addresses from your mailing lists.
- Domain Configuration: Ensure the email domain is correctly configured to receive email.
- Server Blocks: Check if the sending server is blocked by the receiving mail server.
Expert view
Expert from Spamresource.com explains that a "No Such User" error (or similar variations like "User unknown", "Invalid recipient", "Recipient address rejected") usually signifies that the email address you're trying to reach doesn't exist on the mail server. This can be due to typos in the email address, the account being closed, or the domain itself not being properly configured to receive email. It can also happen if the sending server is blocked.
27 Jun 2023 - Spamresource.com
Expert view
Expert from Word to the Wise shares that list hygiene is a huge part of avoiding bounces including 'No Such User' bounces. Regularly cleaning your email list and removing inactive or invalid addresses is crucial. Also checking for updated domain records will help.
17 Dec 2021 - Word to the Wise
What the documentation says
3 technical articles
Gmail 'No Such User' errors, indicated by SMTP error codes 550 and 5.1.1, signal that the recipient's mailbox is unavailable due to the user not existing, the address being incorrect, account suspension/deletion, or routing problems. Proper domain configuration and checking for address accuracy are critical.
Key findings
- SMTP Error Codes: 550 and 5.1.1 error codes indicate 'No Such User' conditions.
- Unavailable Mailbox: The mailbox is inaccessible due to the user not existing or other issues.
- Possible Causes: Incorrect address, account suspension/deletion, and routing problems are possible reasons.
Key considerations
- Address Accuracy: Verify the recipient's email address is correct.
- Account Status: Consider the possibility of the account being suspended or deleted.
- Domain Configuration: Ensure the domain is properly configured for email delivery.
- Routing Issues: Investigate potential routing problems within Google's infrastructure.
Technical article
Documentation from IETF specifies that a 5.1.1 enhanced status code in SMTP responses indicates that the recipient address does not exist. This code is specifically used for 'bad destination mailbox address' scenarios.
12 Jun 2024 - IETF
Technical article
Documentation from Google Workspace Admin Help explains that 'No Such User' bounce messages can indicate that the recipient’s email address is incorrect, the user's account has been deleted or suspended, or there are routing problems within Google's infrastructure. It also suggests checking if the domain exists and is configured correctly.
29 Jul 2021 - Google Workspace Admin Help
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