Why are Gmail accounts bouncing and showing 'No Such User' errors?
Matthew Whittaker
Co-founder & CTO, Suped
Published 29 Apr 2025
Updated 15 Aug 2025
7 min read
When sending emails, few things are as frustrating as seeing a bounce message come back. Among the various types of bounces, the "No Such User" error, often accompanied by a 550 status code, is particularly common with Gmail accounts. This message essentially means that the recipient's mail server, in this case, Google's, cannot find an account corresponding to the email address you tried to reach.
It's a straightforward error, suggesting the email address doesn't exist. However, the reasons behind this seemingly simple message can be more complex than just a typo. Sometimes, it points to deeper issues, such as a deleted account, a temporary server glitch on the recipient's side, or even reputation problems with your sending domain.
Understanding why these bounces occur is crucial for maintaining good email deliverability and ensuring your important messages reach their intended recipients. Let's delve into the common culprits and how to address them effectively.
The primary causes of 'No Such User' bounces
The most frequent reason for a "No Such User" bounce is exactly what the error message implies: the email address simply does not exist. This can stem from several common scenarios that are often overlooked.
A very common cause is a simple misspelling or typo in the recipient's email address. Even a single incorrect character can render an address nonexistent in the eyes of the recipient server. Another frequent scenario involves email accounts that have been deactivated or deleted. People change jobs, companies merge, or individuals abandon old email addresses, leading to these addresses becoming invalid over time. If you're sending to an old or unverified list, the likelihood of encountering such invalid addresses increases significantly.
Sometimes, a recipient might have intentionally blocked your email address or even your entire domain. While this usually results in a different bounce code, in rare cases, a server might interpret it as "no such user" if the blocking mechanism is configured to outright reject the connection before acknowledging the user's existence. Maintaining a clean and verified email list is paramount to avoiding these hard bounces.
The hidden cost of high bounce rates
Frequent "No Such User" bounces are not just missed deliveries; they are a significant indicator to mailbox providers that your sending practices may be subpar. A high bounce rate signals poor list quality or potentially abusive sending, which can lead to a damaged sender reputation, your emails being flagged as spam, or even blocklisting (also known as blacklisting) of your domain or IP address. This directly impacts your ability to reach the inbox for all your communications.
Beyond simple typos: technical and temporary issues
While typos and deleted accounts are common, "No Such User" errors can sometimes point to more technical or transient problems, particularly when dealing with a major provider like Gmail. These issues are less frequent but can cause widespread deliverability problems when they occur.
One such scenario relates to unexpected outages or temporary glitches on the recipient's mail server. Although rare for Google, services can occasionally experience brief interruptions, leading to transient errors. During these periods, valid email addresses might temporarily appear as non-existent. For example, during the December 2020 Gmail outage, many users reported seeing "NoSuchUser" errors for perfectly valid accounts. This highlights the importance of checking status dashboards during unexpected bounce spikes.
DNS misconfigurations, while more typically causing "domain does not exist" errors, can sometimes indirectly contribute to a "no such user" response if the mail server cannot correctly resolve the domain or its MX records. Similarly, issues with email authentication protocols like SPF, DKIM, or DMARC, though usually leading to messages being marked as spam or rejected with different error codes, might occasionally cause a recipient server to refuse to acknowledge a user if the authentication failure is severe enough, especially from less forgiving systems.
Typical 'No Such User' bounce message from Gmailtext
550 5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. Learn more at https://support.google.com/mail/?p=NoSuchUser
Impact on sender reputation and mitigation
Consistent "No Such User" bounces are a clear signal to mailbox providers like Gmail that your sending practices might be problematic. When you repeatedly try to send emails to non-existent addresses, it raises red flags about your list hygiene and overall sender reputation. This can lead to your emails being flagged as suspicious, routed to the spam folder, or even result in your sending IP or domain being added to a blocklist (or blacklist).
Mailbox providers analyze bounce rates as a key metric for determining sender trustworthiness. A high rate of hard bounces, particularly "No Such User" errors, indicates you're sending to old or unverified contacts, which can be perceived as spammy behavior. This negatively impacts your domain reputation, making it harder to reach the inbox for valid recipients. For more information on how email blocklists actually work, you can refer to this guide: how email blacklists actually work.
To mitigate the impact, it's essential to proactively manage your email lists. Implementing a robust list cleaning strategy is vital, including regularly removing invalid or inactive email addresses. Utilizing email verification services before sending can significantly reduce hard bounces. This helps maintain a healthy sender reputation, which is crucial for overall email deliverability.
Common 'No Such User' causes
Typographical errors: Simple mistakes in the email address (e.g., jane.doe@gmial.com).
Deleted accounts: The recipient's email account no longer exists or has been closed.
Expired domains: The domain part of the email address is no longer active.
Recipient blocking: The user or their server explicitly blocked your address, appearing as non-existent.
Effective solutions
List cleaning: Regularly remove hard-bounced addresses from your mailing lists. Consider using an email deliverability tester tool.
Email verification: Use a verification service to validate email addresses before sending campaigns.
Monitor bounce logs:550 5.1.1 Analyze bounce messages for specific error codes like .
Diagnosing the exact cause of a "No Such User" error requires careful examination of the bounce message and your email sending logs. The error message itself often provides clues, such as the specific SMTP error code like 550 5.1.1.
The first step is always to double-check the email address for any typos. This sounds basic, but it's the most common fix. If the address appears correct, review your sending logs. These logs typically contain the full bounce message from the recipient's server, which can offer more detailed information. If you suspect a widespread temporary issue, checking the Google Workspace Status Dashboard can provide insights into any ongoing service disruptions that might affect Gmail deliverability.
For persistent issues, especially if they affect many Gmail addresses, consider the health of your email list and authentication records. High bounce rates can signal a need for more frequent list cleaning or re-verification of your contacts. Additionally, ensure your domain's DNS records, including SPF, DKIM, and DMARC, are correctly configured. These records are critical for proving your emails are legitimate and can help prevent rejections based on perceived suspicious activity.
Implement consistent email list hygiene by regularly removing inactive or bounced addresses.
Utilize email validation services to verify addresses before adding them to your sending lists.
Monitor your bounce rates closely, especially for 'No Such User' errors, and investigate spikes.
Common pitfalls
Ignoring high 'No Such User' bounce rates can severely damage your sender reputation with mailbox providers.
Failing to remove hard bounced addresses from your active mailing lists, leading to repeated failed sends.
Not double-checking email addresses for typos before sending, which is a frequent cause of this error.
Expert tips
If you see a sudden spike in 'No Such User' bounces, cross-reference with major provider status pages.
Segment your email lists and analyze bounce rates by source to identify problematic acquisition channels.
Consider implementing a DMARC policy with reporting to gain deeper insights into authentication failures and bounce reasons.
Expert view
Expert from Email Geeks says they started to see more emails bounce as “NoSuchUser” during a reported Gmail issue, suggesting it was a system-wide problem.
December 14, 2020 - Email Geeks
Marketer view
Marketer from Email Geeks says they experienced a significant increase in "The email account that you tried to reach does not exist" responses from Gmail on a particular day.
December 14, 2020 - Email Geeks
What the 'No Such User' error means for your campaigns
Understanding the "No Such User" error is more than just about fixing a single bounce; it's about maintaining the overall health of your email marketing and communication efforts. Each bounce of this type is a wasted send and, more critically, a signal that your email list might need attention.
By proactively addressing the root causes, from simple typos to underlying technical configurations, you can significantly improve your email deliverability rates. A clean list and properly authenticated emails ensure that your messages have the best chance of landing in the inbox, not the bounce folder. Prioritizing these aspects will lead to more effective communication and a stronger sending reputation with major mailbox providers like Gmail.
One such scenario relates to unexpected outages or temporary glitches on the recipient's mail server. Although rare for Google, services can occasionally experience brief interruptions, leading to transient errors. During these periods, valid email addresses might temporarily appear as non-existent. For example, during the December 2020 Gmail outage, many users reported seeing "NoSuchUser" errors for perfectly valid accounts. This highlights the importance of checking status dashboards during unexpected bounce spikes.
