How to resolve persistent IP reputation issues with Microsoft despite IP warmups and clean lists?
Summary
What email marketers say12Marketer opinions
Email marketer from Tech Support Forum suggests contacting Microsoft support directly to inquire about the specific reasons for the IP reputation issues and request mitigation. They also recommend providing detailed information about the warmup process and list hygiene practices.
Email marketer from Deliverability Discussions recommends analyzing bounce codes received from Microsoft to understand the specific reasons for delivery failures. They suggest addressing the underlying issues identified in the bounce messages.
Email marketer from Email Geeks suggests providing a bounce message example. They also mention the possibility of requesting pre-emptive accommodation from Microsoft for a dedicated IP during warmup to lift limits and monitor the IP.
Email marketer from Email Marketing Forum recommends enrolling in Microsoft's Smart Network Data Services (SNDS) to monitor IP reputation and identify potential sending issues that might be triggering blocks. SNDS provides data on complaint rates and spam trap hits.
Email marketer from Reddit suggests checking the IP's reputation on various blocklists using online tools to identify potential issues affecting Microsoft's servers. They also advise ensuring proper SPF, DKIM, and DMARC records are configured.
Email marketer from SuperUser advises using third-party deliverability testing tools to assess email placement rates and identify potential issues affecting deliverability to Microsoft inboxes.
Email marketer from Email Deliverability Blog advises reviewing email content for spam triggers and ensuring compliance with Microsoft's sending guidelines. They recommend using content analysis tools to identify potential issues.
Email marketer from Email Geeks suggests ensuring pristine data, working with Microsoft through their ticketing process, providing evidence, and building a case for help, as Microsoft is tight-lipped and doesn't actively participate in forums.
Email marketer from Email Geeks explains that an S3150 bounce indicates that part of the sender's network is on Microsoft's block list. They suggest opening a ticket with Microsoft to lift the block if it's a dedicated IP, or having Salesforce do so if it's a shared IP. If the IP repeatedly ends up on the S3150, the marketer suggests to send smaller, high quality traffic to warm up it's reputation far slower than other IPs.
Email marketer from Email Marketing Tips Blog recommends segmenting the email list based on engagement and sending to the most engaged subscribers first to build a positive reputation with Microsoft. Gradually include less engaged segments as the IP reputation improves.
Email marketer from StackOverflow recommends ensuring that reverse DNS (PTR) records are properly configured and match the sending IP address. Mismatched PTR records can negatively impact IP reputation with Microsoft.
Email marketer from SenderScore recommends regularly monitoring Sender Score to assess IP reputation across different mailbox providers, including Microsoft. A low Sender Score indicates potential deliverability issues that need to be addressed. Note that SenderScore is now part of Validity.
What the experts say1Expert opinion
Expert from Word to the Wise explains diagnosing hard bounces can provide important information as to why there are deliverability issues.
What the documentation says4Technical articles
Documentation from Microsoft explains that the S3150 error indicates that part of the sender's network is on Microsoft's block list. They advise contacting your Internet service provider to resolve the issue, providing a link to troubleshooting information.
Documentation from Google explains that although it's for Gmail, monitoring IP reputation through Google Postmaster Tools can give insight. Sudden drops in reputation can be indicative of wider issues that may be affecting sending to other mailbox providers such as Microsoft.
Documentation from ReturnPath recommends setting up feedback loops (FBLs) with Microsoft to receive complaints from recipients. Analyzing FBL data helps identify and remove problematic subscribers, improving IP reputation. Note that ReturnPath is now Validity.
Documentation from SparkPost advises starting with a small sending volume and gradually increasing it over several weeks. It also suggests monitoring bounce rates, complaint rates, and engagement metrics closely to adjust the warmup strategy as needed.