Summary
High BCL scores and junk folder placement are multifaceted, influenced by Microsoft's BCL scoring based on spam complaints, poor sender reputation, lack of email authentication (SPF, DKIM, DMARC), low engagement, spammy content, blacklisting, and sudden sending volume spikes. Addressing these involves warming new IPs/ESPs, ensuring wanted mail through opt-in, improving content quality and engagement, implementing authentication, managing sender reputation and monitoring metrics, and avoiding spam triggers and poor HTML. Crucially, understanding the BCL metric's Microsoft-specific context is important.
Key findings
- Microsoft BCL Score: BCL is a Microsoft-specific score reflecting the likelihood an email is bulk, affecting Office365 filtering. Higher scores increase the chance of junking.
- Sender Reputation is Paramount: Poor sender reputation, stemming from low engagement, high complaints, or blacklisting, is a leading cause of spam folder placement.
- Email Authentication: Implementing SPF, DKIM, and DMARC is essential for verifying sender identity and improving deliverability.
- Engagement Drives Placement: Low open and click rates negatively impact sender reputation, contributing to spam filtering.
- Content Matters: Spammy content, trigger words, and poor HTML significantly increase the risk of emails being marked as spam.
- List Hygiene is Key: Sending to unengaged users harms sender reputation. Opt-in practices and easy unsubscribe options are crucial.
- Volume Spikes Trigger Filters: Sudden increases in sending volume, especially without warming up new IPs, can trigger spam filters.
- Warm-up is Essential: New email streams, whether from a new address or ESP, require a ramp-up period to establish a positive sending reputation.
Key considerations
- Implement Authentication (SPF, DKIM, DMARC): Verify your sending domain with properly configured SPF, DKIM, and DMARC records.
- Create Engaging Content: Craft valuable and relevant content that encourages recipients to open, read, and click.
- Maintain a Clean Email List: Regularly remove unengaged subscribers and ensure a clear opt-in process.
- Monitor Sender Reputation: Track your sending reputation, IP address, and domain for blacklisting and related issues.
- Warm Up New IPs and ESPs: Gradually increase sending volume when using new IP addresses or email service providers.
- Focus on Wanted Mail: Ensure users have explicitly opted in to receive your emails.
- Understand BCL's Scope: Remember that BCL scores are specific to Microsoft's filtering practices.
- Monitor Metrics: Track metrics that influence sender reputation and engagement and ensure any issues are fixed quickly
What email marketers say
9 marketer opinions
Emails land in junk folders with high BCL scores primarily due to poor sender reputation, often stemming from factors like lack of email authentication (SPF, DKIM, DMARC), low engagement rates, high complaint rates, spammy content, blacklisting, and sudden increases in sending volume. Solutions involve improving sender reputation through consistent sending practices, authenticating emails, ensuring valuable and engaging content, cleaning mailing lists, monitoring sending metrics, avoiding spam trigger words and poor HTML, using opt-in lists, and checking/delisting from blacklists.
Key opinions
- Sender Reputation: Poor sender reputation is the most common cause of emails landing in spam. Factors contributing to this include low engagement, high complaint rates, and blacklisting.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) significantly increases the likelihood of emails being marked as spam.
- Engagement: Low open and click rates negatively impact sender reputation and can lead to spam folder placement.
- Content: Spammy content, including excessive use of trigger words, poor HTML coding, and large image sizes, can trigger spam filters.
- List Hygiene: Sending emails to unengaged or uninterested subscribers increases complaint rates and harms sender reputation. Clean and well-maintained lists are essential.
- Sending Volume: Sudden spikes in sending volume, especially without proper IP warming, can trigger spam filters.
Key considerations
- Authentication Implementation: Ensure SPF, DKIM, and DMARC are properly configured and validated for your sending domain.
- Engagement Optimization: Create valuable and engaging content that encourages recipients to open and interact with your emails.
- List Management Practices: Regularly clean your email list by removing unengaged subscribers and implementing a clear opt-in process.
- Sender Reputation Monitoring: Actively monitor your sender reputation, IP address, and domain using available tools and services.
- Blacklist Monitoring and Removal: Check if your domain or IP is blacklisted and take steps to get delisted if necessary.
- Sending Volume Strategy: Gradually increase sending volume over time, especially when using a new IP address or email service provider.
Marketer view
Email marketer from StackOverflow answers by suggesting creating a feedback loop as well as checking spamhaus. It's important to reach out to get delisted to prevent sending problems
10 Dec 2021 - StackOverflow
Marketer view
Email marketer from GlockApps explains that one key reason for emails going to spam folder is poor sender reputation. This can be caused by various factors, including low engagement, high complaint rates, or being listed on blacklists. They suggest monitoring your sending reputation, IP address, and domain using tools like theirs.
21 Apr 2023 - GlockApps
What the experts say
8 expert opinions
High BCL scores and junk folder placement are influenced by several factors. The BCL score, assigned by Microsoft, reflects their confidence in whether an email is bulk, impacting filtering by Office365 customers. While DMARC alignment and custom return paths don't directly affect BCL scores, sending wanted mail, managing sending volume, and warming up new email streams are crucial. New or unwarmed sending streams and sudden volume spikes can trigger spam filters. Engagement is critical as low engagement can lead to emails landing in spam. Focusing on relevant content and ensuring clear opt-in processes and easy unsubscribe options can increase positive sender reputation.
Key opinions
- BCL Scoring: BCL scores indicate Microsoft's confidence in an email being bulk, influencing filtering by Office365 customers. Higher scores increase the likelihood of junking, quarantining, or discarding.
- Warm-up Requirements: New email streams, whether from a new address or ESP, require a warm-up period to avoid being flagged as spam.
- Engagement Importance: Low email engagement (lack of opens/clicks) negatively impacts sender reputation and can lead to spam folder placement.
- Content Relevance: Sending relevant and valuable content encourages recipient interaction and helps maintain a positive sender reputation.
- Sending Volume Impact: Sudden spikes in sending volume without proper IP warming can trigger spam filters.
- Opt-in/Unsubscribe Crucial: Obtaining clear opt-in and honoring unsubscribe requests are critical for ensuring emails are 'wanted' and avoiding spam complaints.
Key considerations
- Sending Wanted Mail: Focus on sending mail only to users who have explicitly opted in, making it wanted rather than unwanted.
- Content Strategy: Craft clear, honest, and easy-to-read content that is relevant and valuable to the recipient.
- Gradual Volume Increase: Warm up new IP addresses and gradually increase sending volume to establish a positive sending reputation.
- Monitor Engagement Metrics: Track open and click rates to identify and address potential deliverability issues.
- List Segmentation: Segment your email list to send more targeted and relevant content to specific groups of subscribers.
- Understand BCL: Understand that BCL is specific to Microsoft and affects filtering within Office365 environments.
Expert view
Expert from Email Geeks states that moving to a new ESP requires a warm-up period because it’s a different email stream.
2 Sep 2024 - Email Geeks
Expert view
Expert from Email Geeks explains that the BCL header is unrelated to DMARC alignment.
13 Apr 2022 - Email Geeks
What the documentation says
4 technical articles
Emails are marked with high BCL scores and land in junk folders due to factors related to sender reputation, authentication, and bulk mail characteristics. Microsoft's Bulk Complaint Level (BCL) indicates the likelihood that a message is bulk mail based on spam complaints, with higher values suggesting a greater chance of generating complaints. Implementing SPF, DKIM, and DMARC authentication, managing sending reputation by minimizing bounces and complaints, and adhering to email content best practices can significantly improve deliverability and prevent emails from being marked as spam. DMARC is a critical defense to verify sender identity.
Key findings
- BCL Interpretation: The Bulk Complaint Level (BCL) indicates the likelihood that a message is bulk mail based on spam complaints.
- Authentication Importance: Implementing SPF, DKIM, and DMARC helps to verify sender identity and improve deliverability.
- Reputation Management: Carefully managing sending reputation by keeping bounce and complaint rates low is critical for inbox placement.
- Content Best Practices: Adhering to email content best practices helps to avoid triggering spam filters.
Key considerations
- Implement SPF, DKIM, and DMARC: Configure SPF, DKIM, and DMARC records correctly to authenticate your sending domain and improve sender reputation.
- Monitor and Manage Sending Reputation: Regularly monitor bounce and complaint rates, and take steps to address any issues promptly.
- Optimize Email Content: Adhere to best practices for email content, such as avoiding spam trigger words and using appropriate formatting.
- Dedicated IP Address: Consider using a dedicated IP address for sending email to better manage your sending reputation.
- Implement DMARC: Implement DMARC to ensure that senders are who they say they are to prevent emails landing in Junk.
Technical article
Documentation from DMARC.org explains that implementing DMARC is a critical defense and the main way to prevent emails landing in junk. It is important to ensure that senders are who they say they are.
3 Nov 2022 - DMARC.org
Technical article
Documentation from Amazon AWS explains that using a dedicated IP address, authenticating your email with SPF, DKIM, and DMARC, carefully managing your sending reputation (keeping bounce and complaint rates low), and adhering to best practices for email content can significantly improve email deliverability and avoid junk folders. Also warm up your IP addresses.
28 Sep 2021 - Amazon AWS Documentation
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