Spam Confidence Level, or SCL, is Microsoft’s proprietary spam score assigned to every email message. This critical metric determines whether your email lands in the Inbox, Junk folder, or is quarantined. The score reflects the degree of suspicion Microsoft 365 and Exchange Online associate with each message.
The SCL scale ranges from -1 to 9, where lower numbers indicate greater trust and higher numbers signal increased risk. While organizational policies can influence an email’s ultimate placement, the SCL score remains the foundational signal in Microsoft’s filtering decisions.
Understanding the specifics of the Spam Confidence Level (SCL) enables more efficient diagnosis of email deliverability issues. Better comprehension of this scale can also provide insights on which mitigation strategies are most likely to improve deliverability outcomes.
To assign an SCL, Microsoft evaluates a multitude of factors. The system incorporates technical authentication results, sender reputation metrics, content analysis, and aggregated user feedback across its entire ecosystem. The overarching objective is clear: to safeguard users by filtering unwanted mail from the Inbox.
Administrators can set allow rules, designate approved senders, or use trusted connectors that assign SCL = -1. This value instructs Microsoft to bypass spam filtering for those messages. Exercise caution with such overrides, as they circumvent standard protections and might conceal genuine deliverability problems.
Administrators retain the ability to configure stricter handling for higher SCL scores. Some organizations enforce quarantine as a default for top scores. Always verify your current policy settings prior to implementing changes.
The SCL rises when technical misalignment or risky sending behaviors are detected. Patterns are often identifiable upon examination of message headers and email history.
Start by enhancing authentication and email infrastructure. These technical adjustments provide the most direct impact on positively influencing your SCL score.
Prioritize these infrastructure elements before making changes to email content. Without proper alignment and a good reputation, content tweaks alone seldom lower your SCL.
A warm up process is recognized by Microsoft’s systems as indicative of a real person sending emails, thus building trust and improving the sender’s reputation. Establishing consistent sending patterns and positive engagement history contributes to progressive SCL improvement.
With Mailwarm, emails are engaged by active inboxes within a managed network: messages are opened, replied to, retrieved from spam, and classified as primary when appropriate. This generates large-scale positive signals and conditions Microsoft’s filters to accept your typical sending profile.
Warm up campaigns are not marketing endeavors, but rather technical measures designed to create favorable activity, reinforce sender reputation, and support a lower SCL.
The Spam Confidence Level of any test message can be confirmed by reviewing its email header, which presents both the assigned score and the key checks performed.
Test repeatedly after each adjustment, monitoring score trends over time, not just individual results.
SCL is a score, not a sentence. Change the inputs, and you change the outcome.
Adopt a straightforward weekly testing routine, focused on message headers and routing outcomes.
Consistent, careful changes are most effective in optimizing both your SCL and sender reputation.
If you would like expert analysis of your message headers, DNS settings, or warm up strategy, we can assist. Initiate a consultation with deliverability specialists at mailadept. Share your latest headers and receive a clear, actionable plan for safely lowering your SCL.
A good SCL score is typically between -1 and 1, indicating emails that are deemed safe and are usually directed to the Inbox. It’s not just about low numbers; organizations should be wary of arbitrary overrides without understanding underlying email infrastructure issues.
Microsoft considers multiple factors, including sender reputation, user feedback, and technical authentication results. Ignoring any of these can lead to false positives or negatives, affecting where your email eventually lands.
An unexpected increase in SCL often signals issues like misconfigured DNS settings, suspicious sender patterns, or poor recipient engagement. Overlooking these can lead to emails being misclassified and quarantined or junked.
While administrators can set overrides to bypass filters, this is a double-edged sword. Such actions can mask underlying problems leading to deliverability issues that, if left unaddressed, can harm sender reputation.
No, tweaking content alone barely makes a dent in the SCL. Prioritizing authentication, ensuring domain alignment, and building engagement are crucial steps to genuinely influence scores.
Review email headers for the SCL value and authentication results by sending test emails to Microsoft mailboxes. Misreading these can lead to inaccurate diagnosis and inappropriate corrections.
Skipping domain warm-up can result in instant flagging by spam filters due to lack of history. This not only increases the SCL but also sets a poor pace for building reputation.
Consistency in sending not only aids in lowering SCL but also keeps sender reputation intact. Erratic patterns can result in suspicion and potential spam classification.
A high SCL can lead to emails being sent to spam or quarantined, hampering communication and affecting business operations. It's essential to tackle this by solidifying your technical setup and sender practices.
