What to do when getting 'not our customer' hard bounce message from Comcast?
Summary
What email marketers say12Marketer opinions
Email marketer from EmailOctopus shares that you need to regularly clean your email list by removing hard bounces. Ignoring hard bounces will increase your bounce rate and damage your sender reputation.
Email marketer from ActiveCampaign shares that after receiving a hard bounce such as “not our customer”, you should immediately remove the recipient from your list to maintain a good sender reputation and avoid future deliverability issues.
Email marketer from SendGrid explains that hard bounces occur for various reasons. Common issues include a non-existent email address, a closed account, or a domain that doesn't exist. The email address is invalid.
Marketer from Email Geeks advises to ignore "not our customer" bounce messages specifically from 3/12 but to generally treat such messages as hard bounces.
Email marketer from Email Marketing Forum emphasizes validating email addresses at the point of entry (signup). Using double opt-in and real-time email verification services can help prevent invalid addresses from ever entering your list, reducing future bounce issues from Comcast and other providers.
Email marketer from HubSpot explains that a high bounce rate signals to ISPs that you may not be following best practices for list hygiene and can result in deliverability issues. This means Comcast would see you as a potential spammer.
Email marketer from Litmus advises to implement strong authentication protocols (SPF, DKIM, DMARC) to improve deliverability. Properly configured authentication can help prevent your emails from being marked as spam, even if some addresses result in 'not our customer' bounces.
Email marketer from StackOverflow recommends implementing a robust bounce handling system that automatically unsubscribes recipients after a hard bounce, especially 'not our customer'. This prevents future sending and maintains a clean list.
Email marketer from Reddit suggests that if you see a sudden spike in 'not our customer' bounces from Comcast, it could be a temporary issue on their end. Monitor the situation and consider temporarily suppressing those addresses, but be ready to re-engage them if the issue resolves.
Email marketer from MailerMailer Blog explains that 'Not our customer' bounce codes, like 5.1.1, typically indicate the email address doesn't exist at the recipient domain. This could be due to typos, account closures, or the address being removed.
Marketer from Email Geeks suggests asking the ESP for the exact bounce message, wondering if the ESP categorized soft bounces as hard bounces due to a temporary issue.
Marketer from Email Geeks shares that one client had a few hundred hard bounces on 3/12 with the message "smtp;550 5.1.1 Not our customer" after previously emailing without issue. They plan to opt one back in to test.
What the experts say2Expert opinions
Expert from Spam Resource explains that a 'not our customer' hard bounce definitively indicates the email address is invalid at that domain. Continued sending to these addresses will negatively impact your sender reputation and may result in blocking.
Expert from Word to the Wise, Laura Atkins, shares that proper bounce processing is crucial. 'Not our customer' bounces should be treated as permanent failures, and addresses should be promptly removed from your mailing list to avoid deliverability issues.
What the documentation says4Technical articles
Documentation from Amazon SES explains that a hard bounce indicates a permanent delivery failure, such as a non-existent email address. Attempting to send to these addresses again will likely result in the same outcome and damage your sender reputation.
Documentation from RFC Editor details that 5.1.1 is a standard SMTP enhanced status code indicating that the recipient address does not exist. It's a permanent error.
Documentation from SparkPost highlights that a 'not our customer' bounce is classified as a hard bounce. These addresses are permanently invalid. Subsequent attempts to send to these addresses will degrade sender reputation.
Documentation from Microsoft Documentation explains that a 5.1.1 NDR (Non-Delivery Report) indicates a bad email address. The recipient's email address couldn't be found.