Can Gmail give false positive SMTP bounce responses?
Summary
What email marketers say7Marketer opinions
Email marketer from Email on Acid explains that bounce errors can be caused by issues with DKIM, DMARC or SPF records. This may lead to false bounces if these records are not properly configured.
Email marketer from Reddit shares anecdotal evidence of encountering situations where Gmail appeared to provide false bounce responses, particularly when dealing with unusual sending patterns or suspected spam-like activity. Suggests verifying the recipient address through alternative channels to confirm its validity.
Email marketer from Digital Ocean explains that many bounces that look like errors are actually temporary errors. This means the user should resend the email at a later date to resolve the issue.
Email marketer from Stack Overflow explains that Gmail rejects emails because the sending IP address has a poor reputation. This can result in emails bouncing back to the sender or being delivered to the spam folder.
Email marketer from Litmus explains that poor list hygiene often leads to bounces. Remove or reconfirm addresses to see if that helps reduce issues. Old addresses may become spam traps.
Email marketer from MailerQ Blog explains that Gmail can sometimes produce misleading bounce messages, particularly 'soft bounces' reported as 'hard bounces'. This might be due to temporary issues, greylisting, or Gmail's spam filtering. Transient network issues or temporary unavailability can also cause false positives.
Email marketer from Sendgrid details that if emails are being sent too fast, Gmail may reject the email. Ensure your sending volumes are within limits.
What the experts say5Expert opinions
Expert from Email Geeks explains that a 2.0.0 SMTP response means the email was accepted into the delivery queue but the end system can't be more specific. A 550 5.1.1 error can occur when the sending system is suspected of spammy activity, being hijacked, or misconfigured. Gmail may also refuse to forward messages due to invalid message IDs. It's important to ensure sending infrastructure is configured correctly and avoid practices Google considers spammy.
Expert from Email Geeks explains the difficulty of cleaning up after a false bounce incident where many legit addresses were suppressed.
Expert from Spamresource explains that bounce codes are not always accurate. Some servers may return generic bounce messages that don't clearly indicate the real problem, or they may temporarily misclassify an issue.
Expert from Word to the Wise explains that temporary errors can cause bounces that look like failures. Try resending later as the server may have been temporarily overloaded.
Expert from Email Geeks shares that Gmail has had past incidents of providing false positive bounce responses, leading to legitimate email addresses being suppressed.
What the documentation says3Technical articles
Documentation from Google Workspace Admin Help explains that Gmail may return a 550 error if the recipient address is invalid, even temporarily. This can happen if a user recently deleted their account or if there's a typo in the address.
Documentation from RFC details that SMTP server can return a variety of codes. A 5xx error means permanent error, while 4xx is temporary. It may be a false positive if a temporary error is issued. Check for other issues.
Documentation from AWS explains that even if you are not an AWS customer, but someone is sending email using AWS SES, then the bounces you get may be due to the reputation of the original sender.