Summary
Hotmail blocks IP addresses due to several factors, primarily related to unwanted email and poor sending practices. These include: sending unsolicited emails/spam, poor list hygiene (spam traps, inactive addresses), high complaint rates (aim for below 0.1%, and a 1% rate on SNDS strongly indicates issues), low engagement, and content triggering spam filters. The underlying cause is a poor sender reputation. Resolution involves identifying the root cause (via SNDS, complaint feedback loops, bounce codes, authentication records), fixing the issues (improving list hygiene, permission practices, engagement), stopping sending to Hotmail, requesting delisting after a pause, and slowly resuming sending. Key to prevention is implementing email authentication (SPF, DKIM, DMARC), warming up new IPs slowly, segmenting lists by engagement, regular list cleaning/verification, ensuring emails are well-designed and accessible, and actively working to improve engagement rates while decreasing unsubscribe/spam rates. When blocked, email is 100% blocked from delivery.
Key findings
- Unwanted Email: Hotmail blocks IPs sending mail users don't want, indicating permission/engagement issues.
- Complaint Threshold: Aim for complaint rates below 0.1%; a 1% rate in SNDS strongly indicates permission or engagement issues.
- List Hygiene is Critical: Poor list hygiene, including spam traps and inactive addresses, contributes heavily to blocking.
- Email Authentication: Lack of SPF, DKIM, and DMARC records increases the likelihood of being blocked.
- Engagement Matters: Low engagement rates lead to poor sender reputation, making it easier to trigger spam filters.
- Bulk Folder Escalation: Blocks often escalate from emails consistently landing in the bulk/spam folder.
- Content Matters: Poorly formatted content and spam triggers are more likely to be blocked.
- Block is Total: When blocked, email is 100% blocked and will not reach inboxes/spam folders.
Key considerations
- Monitor SNDS: Regularly monitor Microsoft's SNDS to track IP reputation and complaint rates.
- Clean Your List: Implement a process to regularly clean and verify your email lists.
- Implement Authentication: Correctly configure SPF, DKIM, and DMARC records for your sending domain.
- Improve Engagement: Segment your lists and send relevant content to improve engagement rates.
- Warm Up New IPs: Slowly warm up new IPs to establish a positive sending reputation.
- Audit Content: Regularly audit email content to ensure it's well-designed, accessible, and free of spam triggers.
- Stop Sending (If Blocked): If blocked, immediately stop sending to Hotmail addresses.
- Request Delisting: After a period of inactivity, request delisting from Microsoft.
- Investigate Root Cause: Determine why the IP was blocked in the first place and take corrective actions.
What email marketers say
9 marketer opinions
Hotmail blocks IPs primarily due to factors indicating unwanted or harmful email practices. These include high complaint rates (aim for below 0.1%), sending unsolicited emails, poor list hygiene (including spam traps and inactive addresses), and content that triggers spam filters. Resolving this requires addressing these issues: implementing email authentication (SPF, DKIM, DMARC), warming up new IPs slowly, segmenting lists by engagement, cleaning and verifying email lists regularly, and improving overall engagement rates while decreasing unsubscribe/spam rates. Monitoring complaint rates via SNDS is also critical.
Key opinions
- Complaint Rates: High complaint rates are a primary driver for Hotmail IP blocks. Aim for a rate below 0.1%.
- List Hygiene: Poor list hygiene, including spam traps and inactive addresses, contributes to blocking.
- Permission Issues: An SNDS reporting of even a 1% complaint rate likely indicates permission problems.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) makes it easier for Hotmail to flag your IP.
- Engagement Matters: Low engagement rates lead to poor sender reputation, resulting in blocklisting. Focus on improving engagement to avoid spam filters.
- Content Matters: Poorly formatted content, use of spam trigger words, images with no ALT text, and broken links increase the likelihood of emails being marked as spam.
Key considerations
- SNDS Monitoring: Regularly monitor SNDS to understand complaint rates and identify potential issues.
- List Cleaning: Implement a process for regularly cleaning and verifying your email lists.
- Authentication Setup: Ensure SPF, DKIM, and DMARC are correctly configured for your sending domain.
- Engagement Strategy: Develop a strategy to improve email engagement, such as segmenting lists and sending relevant content.
- IP Warm-up: If using a new IP address, warm it up slowly to establish a positive sending reputation.
- Content Audit: Review email content to ensure is properly formatted, accessible, and free of spam triggers.
Marketer view
Email marketer from Litmus recommends Regularly cleaning and verifying your email lists can help remove invalid or inactive addresses, reducing bounce rates and the risk of being blocked by Hotmail.
24 Jan 2022 - Litmus
Marketer view
Email marketer from Email Geeks shares that an SNDS reporting a 1% complaint rate would likely indicate permission issues.
3 May 2023 - Email Geeks
What the experts say
6 expert opinions
Hotmail blocks IPs due to sending unwanted mail, leading to poor sender reputation. This often escalates from mail landing in the bulk folder due to inactivity and a lack of engagement. Low engagement, high complaint rates, and poor list hygiene contribute. Resolution involves stopping sending to Hotmail, requesting delisting after a pause, and slowly resuming. Key to prevention and recovery is ensuring permission, improving list hygiene, focusing on relevant content, and investigating the root cause of blocklisting through feedback loops, bounce codes, and authentication records.
Key opinions
- Unwanted Mail: Hotmail blocks IPs that send mail their users don't want, indicating permission or engagement issues.
- Bulk Folder Escalation: Blocking often starts with mail going to the bulk folder due to inactivity and lack of user interaction.
- Low Engagement and Complaints: Consistently low engagement and high complaint rates damage sender reputation and lead to blocking.
- Blocked Mail is Undelivered: When an IP is blocked, mail is 100% blocked and will not reach the inbox or spam folder.
Key considerations
- Stop Sending: When blocked, immediately stop sending to Hotmail addresses.
- Request Delisting: After a pause, request delisting from Hotmail.
- Gradual Resumption: If delisting is successful, slowly resume sending to Hotmail.
- Investigate Root Cause: Analyze complaint feedback loops, bounce codes, and authentication records to identify why you were blocked.
- Improve Engagement: Focus on permission practices, list hygiene, and relevant content to improve engagement and avoid future blocks.
Expert view
Expert from Word to the Wise explains that consistently low engagement rates, high complaint rates, and sending to inactive or invalid addresses lead to poor sender reputation, which results in blocking by ISPs like Hotmail/Outlook. Focus on permission practices, list hygiene, and content relevance to improve engagement.
30 Jul 2024 - Word to the Wise
Expert view
Expert from Email Geeks explains that Hotmail blocks IPs because they think the IPs are sending too much mail that their users don’t want. Thus, the sender should ensure they have permission to send mail and that users are interacting with it.
23 Oct 2023 - Email Geeks
What the documentation says
6 technical articles
Hotmail blocks IPs exhibiting suspicious activity like spam, unsolicited emails, high complaint rates, spam trap hits, and excessive email volume. Sender reputation is critical; maintain it by practicing consistent sending with engaging content. To resolve a block, identify and fix the underlying issue, then submit a delisting request. Use Microsoft's SNDS to monitor your IP's health. Implementing SPF and DMARC is crucial to prevent spoofing, phishing, and to improve deliverability by authenticating your emails.
Key findings
- Suspicious Activity: Hotmail blocks IPs due to suspicious activities like spam, unsolicited emails, and malicious activities.
- Key Metrics: Complaint rates, spam trap hits, and overall email volume are key metrics that contribute to blocking.
- SNDS Monitoring: Microsoft's SNDS program allows senders to monitor their IP's reputation and identify deliverability issues.
- Sender Reputation: Sender reputation is critical for email deliverability; engaging content and consistent practices are crucial.
- Email Authentication: SPF and DMARC records are crucial for preventing spoofing, phishing attacks, and improving deliverability.
Key considerations
- Root Cause Identification: Identify the cause of the block (e.g., high complaint rates or spam traps) before requesting delisting.
- Issue Resolution: Fix the underlying issue (e.g., improve list hygiene or sending practices) before requesting delisting.
- Delisting Request: Submit a delisting request through Microsoft's delisting portal after addressing the underlying issues.
- Consistent Practices: Maintain consistent sending practices and create engaging content to build a positive sender reputation.
- Implement Email Authentication: Implement and correctly configure SPF and DMARC records to protect your domain and improve deliverability.
Technical article
Documentation from Microsoft Support shares that to resolve an IP block, senders should identify the cause of the block (e.g., high complaint rates), fix the issue (e.g., improve list hygiene), and then submit a delisting request through Microsoft's delisting portal.
9 Jun 2022 - Microsoft Support
Technical article
Documentation from Microsoft SNDS explains that senders can use the Smart Network Data Services (SNDS) program to monitor the health and reputation of their sending IP addresses. High complaint rates and spam trap hits are strong indicators of deliverability issues and potential blocking.
25 Jul 2023 - Microsoft SNDS
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