Why are emails sent via Microsoft SMTP going to spam despite good senderscore at other ISPs?

Email marketer from Reddit shares that Microsoft is really strict on their spam filtering algorithms. Suggests making sure you are doing a proper warm up of the IP address associated to your emails, as Microsoft is more likely to flag a new IP as spam.

Email marketer from Sendinblue Blog discusses Microsoft places significant weight on user engagement. If recipients rarely open or interact with your emails, Microsoft’s filters are more likely to classify messages as spam, regardless of Sender Score. Ensure you are using confirmed opt-in, segmenting your lists, and cleaning inactive subscribers to improve engagement metrics. Also make sure you're following deliverability best practices.

Email marketer from Stackoverflow says that the best thing to do is check your domain against blacklists. Also, make sure that you are not on any blocklists.

Email marketer from EmailGeeks shares that Microsoft is super strict on their spam filtering algorithms, and that if emails are going to spam on Microsoft, you may want to check the sender score.

Email marketer from Reddit shares that Microsoft will often flag you as spam if you're not implementing all the newest technologies for email deliverability such as BIMI.

Email marketer from HubSpot Blog discusses Microsoft prioritizes user engagement. It means that even with a good Sender Score, if recipients are not opening and clicking your emails, they are more likely to be marked as spam. So ensure you're segmenting your list and sending personalized content to get better engagement from the users.

Email marketer from Litmus explains that Microsoft might be using its own internal system. They go on to recommend monitoring the Microsoft SNDS (Smart Network Data Services) to understand your reputation specifically within the Microsoft network.

Email marketer from GlockApps Blog shares that Microsoft uses a combination of factors, including sender reputation, content, and user engagement to determine email deliverability. Microsoft may prioritize user engagement more than other ISPs. They advise using their tool to simulate sending an email to different mailboxes to identify deliverability issues.

Email marketer from Mailjet Blog shares that Microsoft has very specific and sometimes opaque filtering practices. Even with a good Sender Score at other ISPs, Microsoft might be using its own internal reputation system or focusing on factors like engagement (opens, clicks) for its users. Also, the content of emails, including links and wording, can significantly impact placement in Outlook or Hotmail inboxes.

Expert from Email Geeks suggests checking SCL and BCL levels in the full headers to diagnose if the issue is a setting implemented by the admin team. It's unlikely to be an IP problem.

Expert from Email Geeks warns that going into spam at Microsoft suggests a potential block. If using Microsoft for outbound mail and facing delivery issues within Microsoft, there should be recourse for investigation. Also advises against using Outlook for marketing messages without proper opt-out methods.

Expert from Email Geeks explains that sender score reputation is based on mail to consumer domains. If you’re sending business mail out O365 then senderscore has zero connection to the IP.

Expert from Email Geeks states that IP reputation doesn’t have much impact on inboxing.

Expert from Spam Resource shares that IP reputation is important, but so is domain reputation and content reputation. There are many different types of reputations that are also important. Microsoft takes all this into consideration when determining what is spam.

Expert from Word to the Wise elaborates that deliverability relies on various factors, including sender authentication (SPF, DKIM, DMARC), list hygiene, content quality, and engagement metrics. Microsoft likely prioritizes these factors over Sender Score when determining spam placement.

Expert from Word to the Wise explains that IP reputation is not the primary factor in deliverability, especially for large providers like Microsoft. Content, authentication, and user engagement signals are more influential.

Documentation from RFC explains that SPF records, DKIM and DMARC records are important and need to be set up correctly in order to ensure Microsoft accepts your email. It may cause Microsoft to throw your emails to spam if not configured correctly.

Documentation from SparkPost explains that Microsoft's SmartScreen filter heavily relies on user feedback. If enough users mark your emails as junk, your deliverability will suffer, even if your Sender Score is good elsewhere. They recommend actively monitoring feedback loops (FBLs) and promptly addressing any complaints.

Documentation from Microsoft details that if you're following all best practices and still encountering delivery issues, the best thing to do is to fill out the sender information form. The team will look to investigate it.

Documentation from Microsoft Learn explains that several factors can contribute to emails landing in spam even with a good sender score. These include: recipient's mail server configurations, spam filtering algorithms, user-reported spam, and the content of the email itself. Microsoft’s Exchange Online Protection (EOP) uses a variety of anti-spam technologies, and these can sometimes misclassify legitimate email. It is important to ensure your SPF, DKIM, and DMARC records are properly configured.