Why are SFMC shared IPs having deliverability issues specifically with Microsoft domains?

Email marketer from Reddit shares that Microsoft's filtering is known to be more aggressive, and shared IPs often bear the brunt of this. Even if your email practices are clean, others on the shared IP could be negatively impacting your deliverability to Microsoft domains.

Email marketer from Litmus mentions that Microsoft pays close attention to user engagement metrics. If recipients frequently mark emails from SFMC shared IPs as spam or delete them without reading, Microsoft's filters will learn to block those IPs.

Marketer from Email Geeks says that key members of the SFMC Abuse team left years ago, which may have lowered the overall quality of mail sent from some shared ranges. Also, Microsoft may be overly heavy-handed or wrong in issuing 550 blocks. Microsoft Support has zero process and resolving an issue is a crapshoot, especially on a shared range.

Email marketer from Email Geeks says it’s related to Microsoft's recorded sending IP history. If using a shared IP, it's a nightmare to resolve. Focus on working with the ESP to get on a reputable IP.

Email marketer from Validity explains that Microsoft uses feedback loops to monitor user complaints. High complaint rates from users receiving emails from SFMC shared IPs can lead to those IPs being blocked or filtered as spam.

Email marketer from GlockApps shares that Microsoft's content filters are sensitive to certain keywords and phrases. If emails sent from SFMC shared IPs frequently contain content flagged as spammy, it can negatively impact deliverability to Microsoft domains, regardless of the sender's individual reputation.

Email marketer from Email Geeks states that the problem will persist as long as shared IPs are used at SF, especially given SF layoffs. Recommends stopping use of a sending system on inbox providers' "not super clean senders" lists.

Marketer from Email Geeks states there is near zero chance of resolving a S3140 error with Microsoft if using Salesforce shared IP network, and that Salesforce needs to deal with the users causing the error and contact Microsoft.

Email marketer from Email on Acid shares that Improper or insufficient IP warmup on SFMC shared IPs can lead to deliverability issues with Microsoft. If a large volume of email is sent from a newly shared IP without gradually increasing the volume, Microsoft might flag it as suspicious.

Email marketer from SparkyPost explains that Shared IPs inherit the reputation of all senders using them. If other senders on the SFMC shared IP are engaging in practices that Microsoft deems spammy, the entire IP range can be penalized, affecting your deliverability.

Email marketer from Sender Score shares that SFMC shared IPs are more likely to appear on blocklists due to the actions of multiple users. Microsoft domains actively use blocklists to filter out spam, and if an SFMC IP is listed, deliverability to Microsoft domains will be severely impacted.

Email marketer from MailerQ shares that Incorrect SMTP (Simple Mail Transfer Protocol) configuration on SFMC shared IPs can cause deliverability issues with Microsoft. This includes issues such as missing or invalid HELO/EHLO greetings, incorrect DNS records, or misconfigured authentication mechanisms.

Email marketer from ReturnPath shares that Consistent monitoring of IP reputation is crucial. Microsoft actively tracks the reputation of sending IPs. If an SFMC shared IP develops a poor reputation due to the actions of other senders, it can lead to deliverability problems specifically with Microsoft domains.

Email marketer from Mailjet shares that Microsoft looks at sending volume and consistency. If the volume from an SFMC shared IP fluctuates wildly or has sudden spikes, it can trigger spam filters, especially if the IP hasn't been properly warmed up for the increased volume.

Expert from SpamResource explains that Microsoft tends to be more sensitive to the overall reputation of shared IPs. This is because shared IPs are used by multiple senders, increasing the likelihood that some senders may engage in practices considered less desirable by Microsoft, leading to filtering issues.

Expert from Word to the Wise explains that Maintaining a good sending reputation is vital for reaching your audience's inboxes. It’s much easier to maintain a good reputation on a dedicated IP than on a shared IP where you have less control over the sending behavior and reputation of the IP.

Expert from Email Geeks says a dedicated IP may get unblocked, and suggests checking the contract for guarantees or mitigations against problems outside control, such as being moved to a shared IP with a better reputation.

Expert from Email Geeks explains Microsoft is aggressive with spam fighting, any fix will be temporary if bad behavior continues. They claim SFMC will not take action unless there's a potential sale from it, and the user will likely have to outgrow the shared IP.

Documentation from Google explains that While focusing on Microsoft, it's important to note the interconnectedness of deliverability. Google's postmaster tools illustrate how IP reputation is a crucial factor for all major ISPs. Poor practices on a shared IP affecting Microsoft deliverability are likely to impact deliverability to other providers as well, due to a general decline in IP reputation.

Documentation from DMARC.org describes if senders using shared IPs do not properly implement DMARC (Domain-based Message Authentication, Reporting & Conformance) policies, it can increase the chances of email spoofing and phishing attacks originating from those IPs. Microsoft is more likely to block or filter emails from IPs with poor DMARC implementation.

Documentation from Salesforce explains SFMC uses shared IP pools for customers who don't have dedicated IPs. Deliverability can be affected when other senders on the same IP pool don't follow best practices. Microsoft's filtering may be more sensitive to shared IPs due to past abuse.

Documentation from RFC Editor explains that Microsoft might be stricter with reverse DNS (rDNS) lookups and domain authentication (SPF, DKIM, DMARC). Shared IPs can sometimes have misconfigured or generic rDNS records, which can negatively affect deliverability to Microsoft domains.

Documentation from Microsoft explains that their SmartScreen filter evaluates sender reputation based on numerous factors, including IP address, domain, content, and user complaints. Shared IPs are more likely to suffer reputation damage due to the actions of multiple senders.