How do I fix the Gmail SMTP error code 5.7.1 and avoid being flagged as spam?

Email marketer from Sendinblue recommends checking your sender score, ensuring your email content isn't triggering spam filters, and verifying your email list for accuracy to prevent 5.7.1 errors.

Email marketer from Mailjet shares that a 5.7.1 error typically means the recipient server suspects spam. They advise warming up your IP address, segmenting your email list, and removing inactive subscribers to improve sender reputation.

Email marketer from StackOverflow user John S explains that if you're sending from a new IP address, Gmail might flag your emails as spam. They suggest gradually increasing your sending volume to build a positive reputation.

Email marketer from GlockApps shares to check if your IP address or domain is on any email blocklists. If you are listed, it provides steps to request delisting and improve your sending reputation.

Email marketer from Email on Acid highlights the importance of monitoring your sender reputation and bounce rates. They recommend using feedback loops to identify and remove subscribers who mark your emails as spam, which helps prevent 5.7.1 errors.

Email marketer from HubSpot emphasizes the importance of permission-based email marketing. They suggest obtaining explicit consent from subscribers, using double opt-in, and providing easy unsubscribe options to maintain a clean email list and avoid spam complaints, which can trigger 5.7.1 errors.

Email marketer from Reddit user u/email_pro shares that you should make sure your emails are properly authenticated with SPF, DKIM, and DMARC. Also, monitor your IP and domain reputation to identify and address any issues.

Expert from Email Geeks explains that Google blocked the emails because they think the mail is spam.

Expert from Word to the Wise Staff explains that SMTP errors such as 5.7.1 may be caused by many different issues including technical setup, DNS settings, Authentication, Blacklisting or reputation.

Expert from Email Geeks shares that the best way to ask is at the point of address collection and confirms that the person giving you the address is the same person who receives mail at that address.

Expert from Spam Resource, Hal Helms explains that senders must maintain a good IP and domain reputation with Gmail, avoiding spam complaints and low engagement. He shares to make sure you are authenticating your emails and following best practices.

Expert from Email Geeks asks if the emails are permission based and authenticated, and if the content could be seen as phishing or spam.

Expert from Email Geeks explains to only send emails people want, when they want them, because they asked for them, and validate who you are to the systems that will be receiving and delivering your email. Make sure that it’s easy to unsubscribe otherwise, they’ll look for other easy methods like the Spam button.

Expert from Word to the Wise, Laura Atkins advises that you can look at the message headers of bounced emails to gain better context for the 5.7.1 error and understand which policy is being violated. Check your authentication too.

Documentation from Google Support explains that SMTP error code 5.7.1 means the message was blocked because it is likely unsolicited mail. They recommend checking the sender's IP address reputation using tools like Sender Score and ensuring proper authentication (SPF, DKIM, DMARC).

Documentation from Microsoft Support explains that a 5.7.1 error often points to issues with sender reputation or authentication. It recommends ensuring that your domain is properly authenticated with SPF, DKIM, and DMARC records.

Documentation from RFC Editor specifies the standard for SMTP status codes and clarifies that 5.7.1 generally indicates a delivery policy violation or that the sender is not authorized to send to the recipient.

Documentation from SparkPost explains that 5.7.1 errors indicate a general delivery issue and suggests reviewing the full error message for specific details about the cause. It also recommends contacting the recipient's email provider for clarification.