Summary
Emails are filtered into Microsoft junk folders due to a confluence of factors, primarily revolving around sender reputation, email content, authentication practices, and recipient engagement. A low sender reputation, often stemming from IP address blacklisting, poor domain reputation, or spam complaints, significantly impacts deliverability. The content of the email itself, particularly the presence of spam trigger words, can also trigger filters. Lack of proper email authentication (SPF, DKIM, DMARC) makes it difficult for Microsoft to verify the sender's legitimacy. User settings, such as marking emails as junk, contribute to filtering decisions. Furthermore, low recipient engagement, including low open rates and click-through rates, negatively impacts sender reputation and overall deliverability.
Key findings
- Sender Reputation Dominance: A poor sender reputation, often due to blacklisting or low IP/domain scores, is the most significant factor in Microsoft's junk mail filtering.
- Content Matters: Email content containing spam trigger words or resembling spam patterns is likely to be filtered.
- Authentication is Key: Proper email authentication (SPF, DKIM, DMARC) is crucial for verifying sender legitimacy and improving deliverability.
- User Feedback Loops: Microsoft's SmartScreen filter utilizes user complaints and feedback to block or redirect emails.
- Engagement Signals: Low recipient engagement rates (opens, clicks) contribute to deliverability issues.
- Shared IP Variable Delivery: Shared IPs may have variable inbox placement even with similar content.
Key considerations
- Monitor & Manage Reputation: Actively monitor sender reputation using tools like Google Postmaster Tools and address any negative signals promptly. Consider IP warming strategies for new IPs.
- Optimize Email Content: Refine email content to avoid spam trigger words, ensure clear messaging, and provide value to recipients. Personalization can help increase engagement.
- Implement Robust Authentication: Set up and maintain SPF, DKIM, and DMARC records to properly authenticate your domain and emails.
- List Hygiene & Consent: Regularly clean your email list to remove unengaged subscribers and ensure you have explicit consent from all recipients. Implement double opt-in.
- Feedback Loop Monitoring: Register for feedback loops (FBLs) with ISPs like Microsoft to identify and remove subscribers who mark emails as spam.
- Engagement Tracking & Segmentation: Track engagement metrics (opens, clicks, spam complaints) and segment your email list based on engagement levels. Send targeted content to engaged subscribers.
What email marketers say
9 marketer opinions
Emails frequently end up in Microsoft junk folders due to a combination of factors relating to sender reputation, email content, authentication, and recipient engagement. Low sender reputation, often resulting from being blacklisted or having a poor IP/domain reputation, significantly impacts deliverability. Email content that contains spam trigger words or resembles spam triggers filters. Insufficient email authentication (SPF, DKIM, DMARC) also increases the likelihood of emails being marked as junk. Poor recipient engagement, such as low open rates or high spam complaint rates, further damages sender reputation and deliverability. List quality and obtaining proper permission from recipients are also vital considerations.
Key opinions
- Sender Reputation: A low sender reputation, due to blacklisting or poor IP/domain rating, is a primary cause of emails being filtered into junk folders.
- Spammy Content: Email content containing spam trigger words or resembling spam can trigger filters and direct emails to the junk folder.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) makes it difficult for Microsoft to verify the sender's legitimacy, leading to filtering.
- Recipient Engagement: Low engagement rates (low opens, clicks) and high spam complaint rates negatively impact sender reputation and deliverability.
- Shared IPs: Shared IPs sending similar content can have variable inbox placement.
Key considerations
- Monitor Sender Reputation: Regularly check your sender reputation using tools like Google Postmaster Tools and address any issues promptly.
- Improve Content Quality: Avoid using spam trigger words, ensure clear and concise messaging, and personalize content to improve engagement.
- Implement Email Authentication: Set up SPF, DKIM, and DMARC records to authenticate your domain and improve deliverability.
- Maintain List Hygiene: Regularly clean your email list by removing unengaged subscribers and ensure you have explicit consent from all recipients.
- Engagement: Track engagement metrics and segment list to only send to engaged recipients.
Marketer view
Email marketer from Reddit explains that emails often go to spam because the sender's IP address is blacklisted, the email content resembles spam, or the domain hasn't been properly authenticated using SPF, DKIM, and DMARC records.
5 Mar 2022 - Reddit
Marketer view
Email marketer from Mailjet explains that a high spam score can be caused by a high spam complaint rate, low engagement, blacklisted IP/domain and the absence of authentication protocols such as SPF, DKIM and DMARC.
23 Jun 2023 - Mailjet
What the experts say
3 expert opinions
Emails are filtered by Microsoft into junk folders primarily due to sender reputation and user complaints. Sender reputation, influenced by IP address, domain, and email content, is a major factor in Microsoft's filtering decisions. Microsoft's SmartScreen filter also blocks or redirects emails based on user complaints. Feedback loops (FBLs) are crucial for identifying and removing subscribers who mark emails as spam, improving overall deliverability.
Key opinions
- Sender Reputation: Sender reputation significantly impacts email deliverability, with Microsoft using it to determine inbox or junk folder placement.
- SmartScreen Filter: Microsoft's SmartScreen filter blocks or redirects emails based on user complaints and negative feedback.
- Feedback Loops (FBLs): FBLs are important for understanding spam complaints, allowing senders to identify and remove problematic subscribers.
Key considerations
- Monitor Reputation: Continuously monitor and manage sender reputation, addressing any negative factors promptly.
- Minimize Spam Complaints: Ensure email content is relevant and desired by recipients to reduce spam complaints.
- Utilize Feedback Loops: Register for FBLs with ISPs like Microsoft to identify and remove subscribers who mark emails as spam.
Expert view
Expert from Word to the Wise explains that feedback loops (FBLs) are important for understanding spam complaints. Registering for FBLs with ISPs like Microsoft allows senders to identify and remove subscribers who mark emails as spam, improving deliverability.
5 Dec 2022 - Word to the Wise
Expert view
Expert from Spamresource explains that sender reputation plays a significant role in email filtering. Microsoft uses sender reputation to determine whether to deliver emails to the inbox or junk folder. Factors such as IP address, domain, and email content contribute to sender reputation.
6 Jan 2025 - Spamresource
What the documentation says
3 technical articles
Emails land in junk folders due to a combination of factors including sender reputation, email content, and authentication issues. A sender's IP address being on a blocklist or having a low reputation score can cause filtering. Additionally, email content triggering spam filters or lacking proper authentication (SPF, DKIM, DMARC) contributes to deliverability problems. User settings, like marking previous emails as junk, also play a role.
Key findings
- Blocklists/Reputation: A sender's IP address being on a blocklist or having a low reputation significantly impacts deliverability.
- Spam Filters: Email content triggering spam filters leads to messages being classified as junk.
- Authentication: Lack of proper authentication (SPF, DKIM, DMARC) makes it difficult for receiving servers to verify the sender's legitimacy.
- User Settings: User settings, such as marking previous emails from a sender as junk, influence future filtering decisions.
Key considerations
- Monitor Blocklists: Check if your IP address is on any blocklists and take steps to be removed if necessary.
- Improve Reputation: Work on improving your sender reputation by adhering to email best practices and providing valuable content.
- Optimize Content: Avoid using spam trigger words and ensure your email content is relevant and engaging.
- Implement Authentication: Set up SPF, DKIM, and DMARC records to properly authenticate your email.
Technical article
Documentation from Microsoft Support explains that emails end up in junk due to factors like the sender's IP address being on a blocklist, the email content triggering spam filters, or the sender not being authenticated properly (SPF, DKIM, DMARC). User settings, like marking previous emails from the sender as junk, also contribute.
9 Nov 2022 - Microsoft Support
Technical article
Documentation from Spamhaus explains that email filtering occurs if your IP address or domain has a low reputation score. Also if your messages contain spam characteristics it will affect it's delivery.
20 Oct 2021 - Spamhaus
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