What are Microsoft SCL and BCL ratings and how do they affect email deliverability?

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
5Marketer 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.

June 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.

January 2023 - StackExchange
Marketer view

Email marketer from Mailjet details that high complaint rates, which affect both SCL and BCL scores, can severely impact deliverability. Microsoft actively monitors complaint rates and uses them as a primary factor in determining email placement. Reducing complaints is crucial for maintaining good deliverability.

December 2021 - Mailjet
Marketer view

Email marketer from EmailVendorSelection.com shares that different organizations may have different thresholds and actions configured for BCL. Some admins may choose to send all mail with a BCL above a certain level to the junk folder, while others may apply less strict filtering. So, the effect of BCL on deliverability varies.

December 2021 - EmailVendorSelection.com
Marketer view

Email marketer from Reddit discusses that a high BCL indicates that your email is considered bulk mail and may be directed to the junk folder or filtered based on admin configurations. A high BCL can negatively impact inbox placement if admins have strict policies in place.

November 2022 - Reddit

What the experts say
6Expert 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.

November 2022 - 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.

September 2023 - Email Geeks
Expert view

Expert from Spam Resource explains that Microsoft's BCL rating is heavily influenced by complaint rates. A high complaint rate will directly result in a higher BCL, impacting deliverability to the junk folder.

February 2024 - Spam Resource
Expert view

Expert from Email Geeks explains that SCL is used in filtering for both consumer and hosted platforms, while BCL is an evaluation done by Microsoft, with filtering done directly by the admin of an O365 hosted domain.

June 2022 - Email Geeks
Expert view

Expert from Email Geeks defines SCL as spam confidence level and BCL as “bad” bulk mail confidence level, which includes greymail.

July 2023 - Email Geeks
Expert view

Expert from Email Geeks states BCL 5 means: The message is from a bulk sender that generates a mixed number of complaints.

June 2023 - Email Geeks

What the documentation says
3Technical 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.

January 2023 - 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.

September 2023 - Microsoft Learn
Technical article

Documentation from Microsoft Learn details that spam is unsolicited and unwanted email, while bulk email is typically marketing or promotional content that users may have opted-in to receive. Microsoft uses different technologies and policies to manage these two categories. Bulk mail is evaluated using BCL, and spam is evaluated using SCL.

July 2022 - Microsoft Learn