Summary
Microsoft's SCL (Spam Confidence Level) and BCL (Bulk Complaint Level) are ratings impacting email deliverability. SCL, ranging from 0-9, predicts the likelihood of an email being spam and is used by EOP and Outlook for filtering. BCL, also ranging from 1-9, identifies bulk email and its potential for generating complaints, with admin-configurable actions. A high SCL often leads to spam classification, while a high BCL may result in junk folder placement, depending on admin settings. High complaint rates significantly increase BCL, affecting deliverability, and sender reputation is crucial for both ratings. Microsoft distinguishes spam (unsolicited) from bulk (opt-in) mail, using SCL and BCL respectively. Best practices to improve deliverability include gaining explicit consent, offering easy unsubscribe options, segmenting lists, monitoring engagement, managing complaints, and maintaining a positive sender reputation.
Key findings
- SCL & BCL Definitions: SCL predicts spam likelihood; BCL identifies potentially problematic bulk mail.
- Scoring Range: Both SCL (0-9) and BCL (1-9) have defined scoring ranges indicating severity.
- Filtering Mechanism: SCL triggers filtering in EOP and Outlook, while BCL is influenced by O365 admin settings.
- Complaint Rate Impact: High complaint rates directly increase BCL, harming deliverability.
- Reputation Significance: A positive sender reputation helps lower both SCL and BCL scores.
- Email Classification: Microsoft differentiates spam from bulk mail, using different assessment methods.
Key considerations
- Consent and Opt-Out: Obtain explicit consent and provide easy unsubscribe options to reduce complaints.
- List Management: Segment email lists and monitor engagement to improve relevance and reduce complaints.
- Reputation Building: Focus on building and maintaining a positive sender reputation.
- Admin Configuration Awareness: Understand that BCL filtering varies based on recipient organization's admin settings.
- Complaint Monitoring & Management: Monitor and actively manage complaint rates to improve BCL and overall deliverability.
What email marketers say
5 marketer opinions
Microsoft's SCL and BCL ratings significantly impact email deliverability. A high SCL increases the likelihood of emails being classified as spam, preventing inbox delivery. A high BCL indicates bulk mail status, leading to junk folder placement based on admin-configured filtering policies. The effects of BCL vary across organizations due to different threshold settings. To maintain deliverability, obtaining explicit consent, providing easy unsubscribe options, segmenting email lists, monitoring engagement, and reducing complaint rates are crucial.
Key opinions
- SCL impact: High SCL scores lead to increased spam classification and reduced inbox delivery.
- BCL impact: High BCL scores result in junk folder placement depending on admin configurations.
- Varied BCL thresholds: Organizations implement different BCL thresholds, affecting deliverability differently.
- Complaint rate: High complaint rates negatively impact both SCL and BCL, severely affecting email placement.
Key considerations
- Consent: Obtain explicit consent from subscribers to avoid high BCL scores.
- Unsubscribe options: Ensure easy unsubscribe options to reduce complaint rates.
- Segmentation: Segment email lists for relevant content to improve engagement.
- Engagement monitoring: Monitor engagement metrics and remove inactive subscribers to maintain deliverability.
- Complaint management: Actively manage and reduce complaint rates to improve both SCL and BCL scores.
Marketer view
Email marketer from GMass shares tips that to avoid high BCL scores, make sure to get explicit consent from subscribers, ensure easy unsubscribe options, segment lists to send relevant content, and monitor engagement metrics to remove inactive subscribers. High complaint rates can significantly increase your BCL.
17 Dec 2022 - GMass
Marketer view
Email marketer from StackExchange explains that a high SCL score means your email is more likely to be classified as spam and not delivered to the inbox. SCL affects deliverability by influencing whether an email reaches its intended recipient or is filtered out.
1 Mar 2023 - StackExchange
What the experts say
6 expert opinions
Microsoft's SCL (Spam Confidence Level) and BCL (Bulk Complaint Level) are ratings that significantly impact email deliverability. SCL indicates the likelihood of an email being spam, influencing filtering on both consumer and hosted platforms. BCL, on the other hand, evaluates bulk mail and its potential to generate complaints, with filtering managed by the O365 domain admin. High complaint rates heavily influence BCL, leading to potential junk folder placement. Sender reputation is a crucial factor for both ratings; a good reputation lowers SCL and BCL, enhancing inbox placement, while a poor reputation results in higher scores and filtering.
Key opinions
- SCL Definition: SCL indicates the probability of an email being spam.
- BCL Definition: BCL indicates the likelihood of bulk mail generating complaints.
- Filtering Control: BCL filtering is managed by the O365 domain administrator.
- Complaint Rate Influence: High complaint rates directly increase BCL, impacting deliverability.
- Reputation Impact: Sender reputation significantly affects both SCL and BCL scores.
- BCL 5 Meaning: BCL 5 indicates a bulk sender generating a mixed number of complaints.
Key considerations
- Monitor Complaint Rates: Closely monitor and manage complaint rates to avoid high BCL scores.
- Improve Sender Reputation: Focus on improving sender reputation to achieve lower SCL and BCL scores.
- Understand Filtering Policies: Be aware of how different O365 admins might configure BCL filtering policies.
Expert view
Expert from Word to the Wise discusses that sender reputation plays a crucial role in both SCL and BCL. A positive sender reputation helps in achieving lower SCL and BCL scores, improving inbox placement. Poor reputation leads to higher scores and filtering.
8 Aug 2024 - Word to the Wise
Expert view
Expert from Email Geeks shares that SCL is based on how likely Microsoft thinks an email is to be spam. BCL indicates whether the mail is bulky and the degree to which the sender tends to cause complaints.
28 Feb 2025 - Email Geeks
What the documentation says
3 technical articles
Microsoft's SCL (Spam Confidence Level) and BCL (Bulk Complaint Level) are ratings used to assess email. SCL predicts the likelihood of an email being spam, ranging from 0 to 9, and is used by EOP and Outlook for filtering. BCL identifies bulk email and its potential for generating complaints, also ranging from 1 to 9. Admins can configure actions based on BCL thresholds. Microsoft differentiates spam (unsolicited, unwanted) from bulk email (opt-in marketing/promotional content) and uses different policies and technologies to manage each, with SCL for spam and BCL for bulk mail.
Key findings
- SCL Definition: SCL predicts the probability of an email being spam, ranging from 0 to 9.
- BCL Definition: BCL identifies bulk email and its potential for generating complaints, ranging from 1 to 9.
- Admin Configuration: Administrators can configure actions based on BCL thresholds.
- Spam vs. Bulk: Microsoft differentiates between spam (unsolicited) and bulk email (opt-in).
- Evaluation Methods: SCL is used to evaluate spam, while BCL is used to evaluate bulk mail.
Key considerations
- Threshold Settings: Understand the SCL and BCL thresholds and their impact on email filtering.
- Email Categorization: Properly categorize emails as either transactional, bulk or marketing.
- Admin Policies: Consider how admin policies on BCL will affect the delivery of bulk emails.
Technical article
Documentation from Microsoft Learn describes that the SCL (Spam Confidence Level) rating predicts the probability that a specific message is spam. SCL ratings range from 0 to 9, where higher values indicate a greater probability that a message is spam. These ratings are used by Exchange Online Protection (EOP) and Outlook to filter spam.
26 Jun 2024 - Microsoft Learn
Technical article
Documentation from Microsoft Learn explains that the BCL (Bulk Complaint Level) helps identify bulk email and assess its potential to generate complaints. It ranges from 1 to 9, with higher values indicating a greater likelihood of complaints. Admins can configure actions based on BCL thresholds.
24 Dec 2022 - Microsoft Learn
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