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Summary

When Gmail accounts start bouncing with "No Such User" errors, it typically indicates that the recipient's email address is invalid or non-existent. However, as experienced during intermittent outages, these errors can also be a symptom of temporary service disruptions on Google's end, leading to what appear to be false invalid user bounces.

What email marketers say

Email marketers frequently encounter "No Such User" bounces, and when these errors surge unexpectedly from Gmail accounts, it often points to a larger system-wide problem rather than individual invalid addresses. Marketers report seeing significant hits to deliverability and widespread false bounces during such incidents.

Marketer view

Marketer from Email Geeks reports that some people and ESPs are observing Gmail having issues again, specifically noting an increase in emails bouncing as "NoSuchUser" errors.

14 Dec 2020 - Email Geeks

Marketer view

Marketer from InMotion Hosting Support suggests that encountering a "550 No Such User Here" error when sending an email indicates that the recipient's mail server cannot locate the specified email address.

1 Mar 2023 - InMotion Hosting Support Center

What the experts say

Deliverability experts recognize that while "No Such User" errors are typically permanent indicators of an invalid address, widespread occurrences from a major provider like Gmail often signify underlying system-wide issues. Their insights focus on distinguishing these anomalies from standard list hygiene problems and applying appropriate diagnostic and mitigation strategies.

Expert view

Expert from Email Geeks (aiverson) reported observing impacted timeframes for Gmail bounces between 2:30 PM and 5:00 PM PT, based on data from a small sample of their clients.

15 Dec 2020 - Email Geeks

Expert view

Expert from SpamResource suggests that a sudden surge of 550 errors, particularly "no such user" bounces, from a major internet service provider might indicate an internal system problem rather than a decline in list quality.

10 Jan 2023 - SpamResource

What the documentation says

Official documentation from various mail providers and technical resources consistently defines the "No Such User" error (typically 550 5.1.1) as a clear indication that a recipient's email address does not exist. While this is generally a permanent bounce, some documentation implicitly acknowledges that system outages can lead to transient delivery issues, which might manifest with similar error types.

Technical article

Documentation from InMotion Hosting Support explains that the 550 "No Such User Here" email error indicates the recipient's mail server is unable to locate the specified email address, leading to a bounce.

1 Mar 2023 - InMotion Hosting Support Center

Technical article

Documentation from Ultahost Knowledge Base outlines that the "550 No Such User Here" email error typically occurs due to common reasons such as a simple typo in the email address, an invalid address provided by the recipient, or the recipient's email account having been terminated.

20 Aug 2024 - Ultahost Knowledge Base

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