Summary
A dedicated IP may be immediately blocklisted by Hotmail during IP warming due to several factors. These include a pre-existing negative IP history or Hotmail's aggressive filtering of new IPs. Other contributing factors are inadequate IP warming (failing to gradually increase volume), issues with the network neighborhood's reputation, missing or incorrectly configured DNS records (SPF, DKIM, DMARC), hitting spam traps, failing to proactively engage with mailbox providers, and not requesting preemptive accommodation from Microsoft. Maintaining list hygiene, monitoring IP reputation, adhering to SMTP standards, and utilizing seed list testing are essential for successful IP warming.
Key findings
- Pre-existing History: The IP may have a pre-existing negative sending history affecting deliverability.
- Aggressive Filtering: Hotmail/Outlook aggressively filters new IPs, requiring careful warm-up.
- DNS Configuration: Incorrect or missing SPF, DKIM, and DMARC records cause immediate blocking.
- Rate Limiting: Hotmail uses strict rate limiting for new IPs.
- Spam Traps: Hitting spam traps leads to immediate blacklisting.
- No Sending History: New IPs have no sending history, requiring gradual reputation building.
- Lack of Preemptive Accommodation: Failing to request Microsoft preemptive accommodation can cause immediate issues
Key considerations
- Check Reputation: Use tools to check IP reputation before warming.
- Verify DNS: Ensure SPF, DKIM, and DMARC records are correctly configured.
- Gradual Warming: Implement a phased IP warming approach.
- Monitor Deliverability: Monitor deliverability via feedback loops and testing.
- List Hygiene: Maintain a clean list and manage bounces and unsubscribes.
- SMTP Compliance: Ensure adherence to SMTP standards.
- Microsoft Communication: Request preemptive accommodation from Microsoft.
- Seed List Testing: Utilize seed list testing to identify potential blacklisting issues
What email marketers say
13 marketer opinions
A dedicated IP might land on Hotmail's blocklist on day one of IP warming due to several reasons. The IP might have a pre-existing negative history, or Hotmail's algorithms might be particularly sensitive to new IPs. Inadequate IP warming procedures (not gradually increasing volume), poor network neighborhood reputation, missing or incorrect DNS records (SPF, DKIM, DMARC), hitting spam traps, and failing to engage in proactive monitoring and feedback loops with mailbox providers are also contributing factors. Regular list hygiene, A/B testing for improved engagement, and pre-emptive communication with Microsoft are also important.
Key opinions
- Pre-existing Reputation: The IP address may have had a poor sending reputation due to its previous usage.
- Aggressive Filtering: Hotmail/Outlook are known to be aggressive with new IPs, requiring careful warm-up.
- DNS Configuration: Missing or improperly configured SPF, DKIM, and DMARC records can lead to immediate blocking.
- Volume Sensitivity: Hotmail's rate-limiting assigns volume per IP per day and often initially blocks new IPs.
- Spam Traps: Hitting spam traps can result in immediate blacklisting.
Key considerations
- Check IP Reputation: Use tools like Sender Score to assess the IP's reputation before warming.
- Verify DNS Records: Ensure SPF, DKIM, and DMARC records are correctly configured.
- Gradual Warming: Implement a phased approach to IP warming, gradually increasing sending volume.
- Monitor Deliverability: Proactively monitor deliverability through feedback loops and seed list testing.
- List Hygiene: Maintain a clean email list by properly handling bounces and unsubscribes.
- Proactive Communication: Request pre-emptive accommodation from Microsoft.
Marketer view
Email marketer from SendGrid responds that gradually increasing sending volume and frequency while maintaining consistent patterns helps build a positive reputation and avoid triggering spam filters.
18 Mar 2023 - SendGrid
Marketer view
Email marketer from GMass suggests that hitting spam traps can immediately blacklist an IP, so maintaining a clean list and following best practices for email acquisition is essential.
23 Jun 2021 - GMass
What the experts say
4 expert opinions
Experts suggest that one primary reason for a dedicated IP being immediately blocklisted by Hotmail during IP warming is the lack of preemptive communication and accommodation requests made to Microsoft. They recommend reaching out to Microsoft, using specific language related to IP warming, and potentially filling out a form to provide projected sending volumes. Seed list testing services are also suggested to identify pre-existing blacklistings.
Key opinions
- Hotmail's Nature: Hotmail's inherent filtering tendencies can lead to initial blocks.
- Preemptive Accommodation: Failing to request preemptive accommodation from Microsoft is a significant factor.
- Seed List Utility: Seed list testing can identify pre-existing blacklisting issues.
Key considerations
- Microsoft Communication: Reach out to Microsoft with specific IP warming language.
- Form Submission: Complete Microsoft's required forms with projected volumes.
- Testing Services: Utilize seed list testing services.
Expert view
Expert from Spam Resource responds explaining that a possible reason for being blocked immediately is not requesting pre-emptive accommodation from Microsoft, and provides details on how to do so.
7 Sep 2021 - Spam Resource
Expert view
Expert from Email Geeks responds that it is Hotmail being Hotmail and suggests reaching out and using a certain magic phrase to inform them that you’re trying to do IP warming, then directs them to <https://www.spamresource.com/2021/05/requesting-pre-emptive-accommodation.html>.
30 Mar 2024 - Email Geeks
What the documentation says
4 technical articles
According to documentation from Microsoft, SparkPost, Google Postmaster Tools, and RFC, a new dedicated IP might be immediately blocklisted due to a lack of sending history, failing to gradually increase sending volume during IP warming, and not adhering to SMTP standards for email formatting. Monitoring IP reputation is also critical for maintaining deliverability.
Key findings
- No Sending History: New IPs lack a sending history, making reputation establishment crucial.
- Phased Approach: IP warming requires a phased approach with gradually increasing volume.
- Reputation Monitoring: Monitoring IP reputation using tools like Google Postmaster Tools is essential.
- SMTP Compliance: Adhering to SMTP standards is vital to avoid being flagged as spam.
Key considerations
- Gradual Volume Increase: Gradually increase sending volume to establish a positive reputation.
- Monitor Deliverability: Monitor deliverability and engagement metrics during IP warming.
- Utilize Postmaster Tools: Use Google Postmaster Tools to monitor IP reputation.
- Adhere to Standards: Ensure emails adhere to SMTP standards for formatting.
Technical article
Documentation from Google Postmaster Tools underlines the importance of monitoring your IP's reputation using their tools, as this directly impacts deliverability to Gmail users (and provides insight into general reputation).
14 Nov 2021 - Google Postmaster Tools
Technical article
Documentation from Microsoft Documentation states that new IPs have no sending history, so it's crucial to establish a positive reputation by gradually increasing sending volume and maintaining good sender practices.
16 Nov 2022 - Microsoft Documentation
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