What caused the Gmail bounce error '550-5.7.1 our system has detected that this message is likely unsolicited mail' and what should I do?

Email marketer from Litmus explains that a good list quality prevents the 550 5.7.1 error. By cleaning your list and only sending to engaged users prevents hitting spam traps and hard bounces.

Marketer from Email Geeks shares the bounce error message being received: "550-5.7.1 [1.2.3.4 12] Our system has detected that this message is 550-5.7.1 likely unsolicited mail. To reduce the amount of spam sent to Gmail, 550-5.7.1 this message has been blocked. Please visit 550-5.7.1 <https://support.google.com/mail/?p=UnsolicitedMessageError> 550 5.7.1 for more information. m22si31676271725pjr.168 - gsmtp"

Email marketer from Sender shares that the 550 5.7.1 error means Gmail is blocking your email. Check your sender reputation, email content, and authentication to fix it. Avoid spam trigger words, ensure proper list hygiene and allow users to unsubscribe.

Marketer from Email Geeks shares that he can't imagine any ESP/MTA would have treated Google's SMTP response as transient. Google has a similar 421 SMTP response they issue when a message should/can be retried - `421-4.7.0 [ IP ADDRESS ] Our system has detected that this message is suspicious due to the very low reputation of the sending domain. To best protect our users from spam, the message has been blocked. Please visit <https://support.google.com/mail/answer/188131> for more information- gsmtp`

Email marketer from Reddit highlights that a sudden increase in email volume can trigger this error. Slowly ramp up your sending volume to establish a consistent sending pattern and reputation.

Email marketer from Email Marketing Forum suggests that if using a dedicated IP address, check its reputation. A newly acquired or previously used IP address with a bad reputation can trigger this error.

Email marketer from GlockApps shares that failing to provide an easy and clear unsubscribe option can cause recipients to mark your emails as spam, leading to this error. Ensure a visible and functional unsubscribe link in every email.

Email marketer from Sendinblue explains that warming up an IP address for sending is important in preventing the 550 5.7.1 error, by gradually increasing sending volume.

Email marketer from Stack Overflow explains that failing to properly configure SPF, DKIM, and DMARC records can lead to this error. Ensure these authentication methods are correctly set up in your DNS settings.

Marketer from Email Geeks shares that ESPs may retry the message after a bounce like the one Gmail was issuing, so it’s possible that after a couple of bounces over a few hours, it then went through.

Email marketer from Mailjet shares the 550 5.7.1 error indicates that your email was rejected due to spam-like characteristics. You should review your sender reputation, IP address, email content and authentication to solve the issue.

Email marketer from Reddit points out that sending to old or unengaged lists can cause this error. Clean your email list regularly to remove inactive subscribers and spam traps.

Email marketer from Campaign Monitor suggests regularly cleaning your email list of invalid or inactive addresses. This avoids sending to spam traps and reduces the likelihood of 550 5.7.1 errors. It includes best practices for managing bounces.

Email marketer from EmailOctopus explains the 550 5.7.1 error from Gmail usually flags a problem with spam. You can try improving your sender reputation, ensure your email content doesn't have spam triggers, implement authentication protocols and ensure you have consent from your subscribers.

Marketer from Email Geeks explains Google will not retroactively reverse course on the bounces. Check with your vendor to see if they will resend as some are unable to. If the vendor doesn't resend, you may need to resend the emails yourself.

Expert from Word to the Wise suggests cleaning your lists from old or unengaged users. This can negatively impact the deliverability of your email and cause a 550 5.7.1 error due to reputation issues.

Expert from Word to the Wise explains the 550 5.7.1 error usually means there is a problem with the sender’s reputation. It points out that improving sender reputation by authenticating your email and ensuring you are following email best practices can prevent it.

Expert from Spam Resource explains that the 550 5.7.1 error often indicates that a content filter has flagged the email. Review the email content for spam-like keywords or phrases that may be triggering the filter.

Documentation from Google Support explains the 550 5.7.1 error indicates Gmail detected the message as unsolicited. Google recommends checking your sending practices, ensuring proper authentication (SPF, DKIM, DMARC), and reviewing their bulk sender guidelines.

Documentation from RFC Editor explains that SMTP enhanced status codes, like 5.7.1, provide standardized feedback about delivery problems. It points to security or policy issues that prevent message delivery and the full RFC describes the meaning of each number.

Documentation from SparkPost explains the 550 5.7.1 error means Gmail considers the message as spam. This is based on sender reputation, content, and authentication. They suggest improving these areas for better deliverability.

Documentation from Microsoft explains the 550 5.7.1 error indicates a spam or policy violation. To resolve, review your email content, sending practices, and ensure compliance with anti-spam policies.