How can I re-evaluate a domain's SCL and BCL with Microsoft?
Michael Ko
Co-founder & CEO, Suped
Published 21 Jun 2025
Updated 17 Aug 2025
7 min read
Dealing with email deliverability issues, especially with major providers like Microsoft, can be frustrating. Many senders find their emails landing in the junk folder, even when their authentication records seem perfectly configured. A common culprit behind this is often related to a domain's Spam Confidence Level (SCL) and Bulk Complaint Level (BCL) scores assigned by Microsoft's filtering systems.
The challenge intensifies when attempting to get these scores re-evaluated. My experience, and that of many others, shows that directly requesting a domain's SCL or BCL reset through Microsoft's Postmaster (or other) forms usually yields responses focused on IP addresses, not domain reputation. This article aims to clarify why that is, and more importantly, outline the actual steps you can take to influence and improve your domain's SCL and BCL with Microsoft.
Understanding SCL and BCL in Microsoft 365
Before diving into re-evaluation, it is essential to understand what SCL and BCL are and how Microsoft uses them. These scores are crucial indicators of your email's trustworthiness and impact its inbox placement. For more foundational knowledge, you can read our guide on what Microsoft SCL and BCL ratings are.
The Spam Confidence Level (SCL) is a rating assigned to individual inbound messages by Microsoft 365's spam filtering. A higher SCL value, typically ranging from 0 to 9, indicates a greater likelihood that the message is spam. Based on this score, Microsoft 365 takes action on the message, which could be moving it to the junk folder, quarantining it, or rejecting it outright, depending on the anti-spam policy configurations.
The Bulk Complaint Level (BCL) is a separate value assigned to inbound messages that originate from bulk senders. It reflects the sender's reputation for sending bulk email. A higher BCL value, also typically from 0 to 9, indicates that the bulk email is more likely to generate complaints from users. Similar to SCL, a high BCL can lead to messages being delivered to the junk folder or being blocked. While SCL is about the spamminess of a specific email, BCL is about the reputation of a bulk sender's domain (or IP) based on past complaint rates.
Metric
What it assesses
Score range
Typical outcome
SCL (Spam Confidence Level)
Spam likelihood of a single message based on content, headers, and sender reputation.
-1 to 9 (Higher = more spam-like).
Inbox, junk folder, quarantine, or rejection.
BCL (Bulk Complaint Level)
The complaint rate from bulk emails associated with a specific sender's domain or IP.
0 to 9 (Higher = more complaints).
Inbox (with lower priority), junk folder, or rejection.
Why direct re-evaluation is challenging
The direct re-evaluation of a domain's SCL or BCL score with Microsoft is not as straightforward as requesting an IP de-listing from a blocklist (or blacklist). Microsoft's Postmaster tools and support channels are primarily geared towards IP-based issues, not domain-level reputation metrics like SCL and BCL.
These scores are dynamic and are assigned based on a complex array of factors after the email has been accepted by Microsoft's Exchange Online Protection (EOP). This means that a high SCL or BCL typically results in messages being moved to the junk folder, rather than being outright rejected or bounced, unless the score is exceptionally high or combined with other severe policy violations. This distinction is crucial, as bounces often indicate an IP or severe blocklist issue, while junking points to domain or content reputation problems.
Therefore, if you're experiencing emails landing in the junk folder with high SCL or BCL values, the solution isn't a simple request for a reset. It requires a more comprehensive approach to improving your overall sender reputation over time. You might want to refer to our guide on how to fix Outlook junk mail placement for more insights.
Why direct re-evaluation is unlikely
Microsoft's SCL and BCL scores are determined by sophisticated algorithms that assess numerous factors related to sender reputation, content, and recipient engagement. These are not static values that can be manually reset via a support ticket. Instead, they reflect your ongoing sending practices. Any improvements will be recognized organically by their systems over time, as your sending behavior aligns with best practices.
Strategies for improving SCL and BCL
Since direct re-evaluation is not an option, the most effective strategy is to proactively improve your domain's email sending reputation. This involves a multi-faceted approach addressing all the signals Microsoft's filters consider. If you are facing broad issues with deliverability to Microsoft domains, our guide on how to resolve email blocking issues can provide further assistance.
First, ensure your email authentication is impeccable. This includes properly configured SPF, DKIM, and DMARC records. These protocols verify that your emails are legitimate and prevent spoofing, which is a significant factor in reputation. Microsoft heavily relies on these signals to trust incoming mail. You can also review DKIM temporary error rates that may occur with Microsoft.
Secondly, focus on the quality of your email content and recipient engagement. Avoid spammy keywords, excessive links, or suspicious formatting. Encourage recipients to engage with your emails by opening, clicking, and replying, and make it easy for them to add you to their safe sender list. Crucially, regularly clean your email lists to remove inactive or invalid addresses, which can lead to bounces or spam trap hits, damaging your reputation. You can use a free online email testing tool to check your email's placement and identify issues.
Common SCL/BCL issues
Poor authentication: Missing or incorrectly configured SPF, DKIM, and DMARC records.
Low engagement: Recipients rarely open, click, or reply to your emails.
High complaint rates: Users frequently mark your emails as spam.
Spammy content: Subject lines, body text, or links that resemble unsolicited mail.
List quality issues: Sending to outdated lists, purchased lists, or containing spam traps.
Solutions for improvement
Implement DMARC: Enforce strict policies (p=quarantine or p=reject) to prevent spoofing and gain visibility. Our DMARC record generator can help.
Segment audiences: Send targeted emails to engaged subscribers to minimize complaints.
Maintain list hygiene: Regularly remove unengaged users and invalid addresses. Avoid purchased lists.
Monitor blocklists: While SCL/BCL aren't direct blocklists, being on a major blocklist will worsen your reputation. Use blocklist monitoring tools.
Monitoring and long-term maintenance
Continuous monitoring of your email deliverability is key to maintaining a good domain reputation. This includes regularly analyzing your email headers for SCL and BCL values, which can provide insight into how Microsoft is currently rating your messages. You can use this information to identify trends and pinpoint specific issues.
When an email is received by Microsoft 365, various anti-spam headers are added, including the SCL and BCL scores. You can examine these headers to understand the verdict Microsoft's filters have assigned. For example, look for the X-Microsoft-Antispam header, which contains the BCL, and X-MS-Exchange-Organization-SCL for the SCL value. Understanding these values helps diagnose where improvements are needed. For deeper analysis, consult our guide on how to interpret SCL scores in Microsoft headers.
Microsoft also offers a feedback loop program known as Sender Support Delegation and Sender Lists (SNDS). Registering your sending IPs and domains with SNDS allows you to monitor your sending reputation and see data on spam complaints directly from Microsoft. This data is invaluable for identifying campaigns or segments that might be generating high complaint rates, enabling you to take corrective action and improve your BCL over time. Maintaining a proactive approach to your sending practices is the only way to genuinely re-evaluate and improve your domain's standing with Microsoft.
Views from the trenches
Best practices
Regularly monitor your email headers for SCL and BCL values to track Microsoft's assessment of your emails.
Implement a strong DMARC policy (p=quarantine or p=reject) to improve domain authentication and reputation.
Segment your email lists and send targeted content to engaged subscribers to minimize complaints and improve positive engagement.
Maintain meticulous list hygiene by frequently removing inactive and invalid email addresses to avoid spam traps and bounces.
Provide an easy and visible unsubscribe option in every email, respecting recipient preferences promptly.
Common pitfalls
Relying solely on Microsoft Postmaster forms for domain-level SCL/BCL re-evaluation, as they primarily focus on IP issues.
Ignoring high SCL/BCL scores, which indicates that emails are still being accepted but routed to the junk folder.
Sending inconsistent email volumes or sudden spikes, which can negatively impact sender reputation with Microsoft.
Using purchased or outdated email lists, leading to high bounce rates and increased spam complaints, damaging BCL.
Failing to monitor engagement metrics, missing opportunities to refine content and sending strategies based on recipient behavior.
Expert tips
Focus on domain-level reputation by ensuring all email authentication methods (SPF, DKIM, DMARC) are correctly configured and aligned.
Prioritize email content quality and personalization to increase positive engagement and reduce spam complaints from recipients.
If your BCL is consistently high, consider reviewing your bulk sending practices and segmenting your audience more effectively.
Leverage Microsoft's Sender Support Delegation and Sender Lists (SNDS) for direct insight into complaint rates and IP reputation data.
Remember that SCL and BCL improvements are cumulative and require sustained adherence to email deliverability best practices.
Expert view
Expert from Email Geeks says they would be surprised if you can request a reset of SCL and BCL via Microsoft Postmaster tickets. The anti-spam team inside the inbox seems to be separate from those managing frontline IP and ASN blocks.
2024-12-25 - Email Geeks
Expert view
Expert from Email Geeks says SCL and BCL are typically added after an email is accepted, and Microsoft does not usually reject emails outright based on high scores. Instead, emails are often directed to the spam folder depending on user settings.
2024-12-25 - Email Geeks
Improving your Microsoft sender reputation
Re-evaluating your domain's SCL and BCL with Microsoft is not a matter of submitting a form for a quick reset, but rather a continuous effort to build and maintain a strong sender reputation. Microsoft's filtering systems are sophisticated, constantly analyzing signals from your email authentication, content, and recipient engagement to determine these scores. The path to improvement lies in understanding these factors and consistently adhering to email deliverability best practices.
By focusing on robust authentication, delivering high-quality and relevant content, managing your subscriber lists meticulously, and actively monitoring your sender performance, you can positively influence your SCL and BCL scores. This proactive and holistic approach will naturally lead to improved inbox placement for your emails within the Microsoft ecosystem, reducing the instances of your messages being classified as junk or spam.
