Summary
Subdomains significantly impact root domain reputation; negative activities on subdomains can negatively influence the overall domain's deliverability. Microsoft O365/Outlook uses SCL (Spam Confidence Level), where a score of 5 or higher suggests a high likelihood of emails landing in the spam folder, typically stemming from poor IP/domain reputation. Key strategies for improvement include ensuring proper email authentication (SPF, DKIM, DMARC), practicing list hygiene, monitoring sender behavior and recipient engagement, and contacting Microsoft support for a delisting or reputation review. Also, analyze email content for spam triggers, gradually warm-up new IPs/domains (if applicable), and avoid using warm-up services as they can harm reputation. To effectively address deliverability issues with Microsoft, persistence is key, involving clearly stating the issue and requesting escalation/reputation reset within the support tickets. Recipient actions such as moving emails out of the spam folder also contribute positively.
Key findings
- Subdomain Impact: Subdomains affect root domain reputation; negative activities on subdomains can negatively impact the root domain.
- SCL 5 Indicates Spam: SCL score of 5 or higher signifies a high likelihood of being filtered as spam in Microsoft O365/Outlook, often due to poor IP/domain reputation.
- Authentication is Key: Proper email authentication (SPF, DKIM, DMARC) is crucial for improving deliverability and sender reputation.
- Microsoft Requires Persistence: Successfully addressing deliverability issues with Microsoft necessitates persistent communication and specific requests (escalation, reputation reset).
- Warm-up Services Harmful: Using email warm-up services is generally not recommended, as they can often harm sender reputation.
Key considerations
- Monitor Engagement: Continuously monitor engagement metrics like bounce rates and spam complaints to proactively manage reputation.
- Practice List Hygiene: Regularly clean email lists to remove inactive/invalid addresses and minimize bounce rates.
- Analyze Content: Thoroughly analyze email content for potential spam triggers and optimize accordingly.
- Gradual IP/Domain Warmup: If introducing new IPs or domains, implement a gradual warm-up process to build a positive sending reputation.
- Engage Recipients: Encourage recipients to move emails from the spam folder to the inbox to improve domain reputation.
What email marketers say
11 marketer opinions
The impact of subdomains on root domain reputation varies. While they can provide isolation for different email streams, negative practices on a subdomain can eventually harm the root domain's reputation. An SCL of 5 in Microsoft O365/Outlook indicates a high likelihood of emails being marked as spam, suggesting a problem with IP/domain reputation or content. Remediation involves proper email authentication (SPF, DKIM, DMARC), list hygiene, monitoring sender behavior and engagement, and contacting Microsoft support for delisting or reputation review. Warming up IPs and domains gradually and avoiding blacklisted content is also crucial. Using warm-up services should be avoided.
Key opinions
- Subdomain Impact: Subdomain activity impacts root domain reputation; negative activity can negatively impact root domain reputation.
- SCL 5 Meaning: SCL 5 indicates high spam likelihood with Microsoft, often due to poor IP/domain reputation.
- Authentication Importance: Proper email authentication (SPF, DKIM, DMARC) is crucial for improving deliverability.
- Microsoft Support: Contacting Microsoft support and requesting a reputation review is advisable to help resolve domain issues.
- Warmup Avoidance: Avoid using warm-up services as they can harm the reputation.
Key considerations
- Monitoring and Engagement: Monitor bounce rates, spam complaints, and engagement metrics to proactively manage reputation.
- List Hygiene: Regularly clean email lists to remove inactive addresses and reduce bounce rates.
- Content Analysis: Analyze email content for spam triggers and optimize for deliverability.
- Gradual Warmup: If using new IPs or domains, warm them up gradually to establish a positive sending reputation.
- Segmentation: Using different subdomains to segment different types of emails can isolate email streams in the event of deliverability issues.
Marketer view
Email marketer from GMass advises to only send emails to recipients who have opted-in and have a genuine interest in receiving your messages. Regularly clean your email list to remove inactive or invalid addresses to reduce bounce rates and improve your sender reputation.
31 Jan 2024 - GMass
Marketer view
Email marketer from Litmus shares that ensuring proper email authentication using SPF, DKIM, and DMARC is crucial for improving deliverability and preventing spoofing. DMARC policies help instruct receiving servers on how to handle emails that fail authentication, preventing malicious use of your domain.
23 Aug 2022 - Litmus
What the experts say
4 expert opinions
Subdomain reputation has an impact on root domain reputation, and issues on subdomains affect the main domain. Addressing Microsoft O365 Outlook SCL:5 spam filtering requires persistent action, including opening tickets with Microsoft and requesting a reputation reset, using specific terms like 'escalation' and 'reputation reset.' Regularly having recipients move emails out of the spam folder is also important. Thoroughly investigate authentication, content, and sending practices when encountering SCL scores of 5 or higher, ensuring proper authentication, list hygiene, and engagement.
Key opinions
- Subdomain Impact on Root: Subdomain reputation affects root domain reputation; issues on subdomains impact the main domain.
- SCL 5 Indicates Spam: SCL scores of 5 or higher indicate a high likelihood of being filtered as spam in Microsoft O365/Outlook.
- Microsoft Requires Persistence: Addressing deliverability issues with Microsoft requires persistent action and specific terminology (escalation, reputation reset) when opening tickets.
- Recipient Action Helps: Encouraging recipients to move emails out of the spam folder and into the inbox can improve domain reputation.
Key considerations
- Investigate Sending Practices: Thoroughly investigate authentication, content, and sending practices for potential spam triggers.
- Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is in place.
- List Hygiene: Maintain good list hygiene practices to reduce bounce rates and improve engagement.
- Engagement: Focus on improving recipient engagement to signal positive sender reputation.
Expert view
Expert from Email Geeks states that subdomain reputation does impact root domain reputation, but the extent to which it can repair a domain's reputation is unclear.
6 Nov 2024 - Email Geeks
Expert view
Expert from Spam Resource shares that when debugging deliverability issues into Microsoft, understand an SCL score of 5 and above indicates messages are highly likely to be filtered as spam. Investigate authentication, content, and sending practices when encountering this score.
26 Mar 2022 - Spam Resource
What the documentation says
4 technical articles
An SCL of 5 indicates that a message is considered highly suspicious and likely spam. To improve sender reputation, ensure proper email authentication (SPF, DKIM, DMARC), maintain low spam complaint rates, avoid invalid email addresses, and avoid spammy content. Properly configured SPF records help receiving mail servers verify that the email is legitimately sent from your domain. If your IP or domain is blocked, use the delist portal, providing accurate information, to request removal.
Key findings
- SCL 5 Definition: SCL 5 signifies a high spam confidence level, indicating a likely spam classification.
- Authentication Importance: Proper email authentication (SPF, DKIM, DMARC) is critical for improving sender reputation.
- SPF Validation: Correctly configured SPF records help verify legitimate sending sources.
- Delisting Process: The delist portal can be used to request removal if your IP or domain is blocked by Microsoft.
Key considerations
- Reduce Spam Complaints: Minimize spam complaint rates to maintain a positive sender reputation.
- List Maintenance: Avoid sending to invalid email addresses by practicing good list hygiene.
- Content Quality: Ensure email content is not spammy and provides value to recipients.
- Delisting Information: Provide accurate and complete information when using the delist portal to improve chances of success.
Technical article
Documentation from Microsoft Learn explains that an SCL (Spam Confidence Level) of 5 indicates that a message is considered highly suspicious and is likely spam. The higher the SCL, the more likely it is that the message will be filtered as spam by Exchange Online Protection (EOP) or Outlook.
22 Feb 2024 - Microsoft Learn
Technical article
Documentation from Microsoft Learn explains that to improve sender reputation, ensure your sending domain is authenticated with SPF, DKIM, and DMARC. Maintain low spam complaint rates, avoid sending to invalid email addresses, and ensure your content is not spammy. Requesting delisting through the delisting portal if blocked is also recommended.
7 Jan 2024 - Microsoft Learn
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