Summary
Using BCC (blind carbon copy) emails, particularly during the crucial IP warming phase, can significantly impact sender reputation and overall deliverability. While seemingly innocuous for internal tracking or record-keeping, the lack of recipient engagement (opens, clicks) for these BCC’d copies can send negative signals to mailbox providers, undermining the very goal of warming up an IP or domain.
Key findings
- Undisclosed engagement: Mailbox providers cannot distinguish a BCC’d email from a regular 'To' recipient. If these copies consistently go unopened or unclicked, it lowers the perceived engagement rate for your sending IP and domain.
- Reputation erosion: Low engagement signals, especially at scale, can erode your sender reputation. This is particularly harmful during IP warming, when you are trying to build trust with ISPs.
- Volume impact: All emails, including BCCs, count towards your total sending volume. If BCC volume is high and unengaged, it inflates your total sends without corresponding positive engagement, potentially leading to deliverability issues.
- ISP scrutiny: Mailbox providers, especially for enterprise emails (like Gmail or Microsoft), scrutinize messages more rigorously if they detect unusual sending patterns or low engagement from a particular source.
Key considerations
- Avoid BCC for bulk sends: BCC is generally not recommended for bulk email or marketing campaigns due to its negative deliverability implications.
- Alternative solutions: If a business reason necessitates copies, explore alternatives like webhooks, API integrations, or CRM logging instead of BCC.
- Internal BCC mitigation: For internal BCCs to owned mailboxes, implement rules to auto-mark as read or move to a folder to simulate engagement. Ensure these mailboxes are not hosted by the same major ISPs you are sending customer emails to, as their internal systems may still track engagement.
- Factor into warming plans: If BCC use is unavoidable, factor the volume sent to enterprise mail servers (e.g., Google or Microsoft) into your IP warming schedule for customer emails. This ensures the total send volume and engagement ratios are realistic.
What email marketers say
Email marketers often face practical challenges that lead them to use BCC, sometimes without fully understanding the deliverability ramifications. Their experiences highlight the trade-offs between business needs and maintaining a healthy sender reputation, especially during sensitive periods like IP warming.
Key opinions
- BCC is generally ill-advised: Many marketers agree that using BCC for bulk emails is problematic and a bad idea for IP warming.
- Engagement signals are key: If BCC'd emails are not opened, it negatively impacts perceived engagement, which can lead to deliverability problems over time, particularly with high volume.
- Real-world impact: Some marketers have observed actual dips in reputation and increased spam folder placement when clients used BCC for internal tracking, especially when combined with other negative factors like reduced sending volume or negative recipient response.
- Internal BCC subtleties: If the internal BCC recipient is hosted by the same ISP (e.g., Gmail, Microsoft 365), that ISP might still factor the lack of engagement into their reputation calculations, even for internal mail.
Key considerations
- Consider sender reputation: Marketers should always prioritize building a strong sender reputation, which is crucial for inbox placement.
- Mitigation for internal BCC: If BCC must be used for internal purposes, explore methods like auto-marking the emails as read or setting up rules to move them to a specific folder to simulate interaction.
- Understand ISP visibility: Be aware that if your internal BCC recipients are on major ISPs like Gmail or Microsoft, those providers may still see the unengaged messages as part of your overall sending behavior.
- Holistic view of deliverability: While BCC can be a factor, it's often one of several elements affecting deliverability. Other issues, such as content, list quality, and recipient response, also play significant roles.
Marketer view
Email marketer from Email Geeks suggests that when a BCC'd email is received by a mailbox provider, it isn't obvious that it's a BCC. The recipient address (the 'To' field) doesn't match the receiving mailbox, and if the message isn't opened, this will negatively influence deliverability, especially at volume.
Marketer view
A marketer from Email Geeks indicates that BCC is generally not advisable for bulk emails and is a very poor choice when attempting to warm up an IP address. It can undermine the reputation-building process.
What the experts say
Deliverability experts consistently warn against practices that can artificially deflate engagement metrics, especially for high-volume sending. BCC use falls into this category, as it introduces unengaged volume that can mislead mailbox providers about the true quality and relevance of a sender's mail stream. This is particularly critical during the delicate IP warming phase.
Key opinions
- Reputation is paramount: Experts agree that sender reputation is the cornerstone of deliverability. Any practice that negatively impacts engagement signals, like widespread BCC usage, directly jeopardizes this reputation.
- IP warming fragility: The IP warming process is sensitive and relies on building consistent positive engagement. Introducing significant unengaged BCC volume can skew these metrics and hinder the warming process.
- ISP sophistication: Modern ISPs use complex algorithms to assess sender behavior. They can detect patterns of low engagement across a large portion of sends, regardless of whether they are BCC'd or direct, impacting inbox placement for all mail from that sender.
- Domain vs. IP reputation: While IP reputation is directly affected by volume and engagement, persistent negative signals from BCCs can eventually harm your domain reputation as well.
Key considerations
- Prioritize genuine engagement: Focus on sending to genuinely engaged recipients. If BCC is necessary for a business function, ensure it doesn't inflate your reported send volume for reputation purposes.
- Monitor engagement metrics closely: During IP warming, vigilantly track open rates, click-through rates, and other engagement metrics. Discrepancies caused by BCC can signal underlying issues.
- Avoid shared IP misuse: On shared IPs, poor practices like heavy BCC usage can impact other senders using the same IP. Conversely, sending cold emails through shared IP addresses can also jeopardize sender reputation.
- Educate internal teams: Ensure all stakeholders understand the deliverability risks associated with BCC and explore alternative solutions for their reporting or archiving needs.
Expert view
Email expert from Email Geeks clarifies that Mailbox Providers (MBPs) treat all recipients, whether in the 'To' or 'BCC' field, as a direct send. If the BCC recipient is within the same MBP domain and doesn't engage, it negatively impacts engagement metrics for that specific MBP, even if the primary recipients engage.
Expert view
An email expert from SpamResource recommends avoiding BCC for any form of bulk or marketing communication because it provides no transparent engagement signals to ISPs. This lack of transparency can lead to poorer inbox placement compared to transparent 'To' or 'CC' sends.
What the documentation says
Official documentation from various email service providers and industry bodies often emphasizes the importance of sender reputation and engagement for deliverability. While specific mentions of BCC are rare in broad guidelines, the underlying principles strongly advise against practices that generate unengaged volume or obscure true recipient interaction, especially during IP warming.
Key findings
- Reputation is dynamic: Documentation from services like MoEngage highlights that establishing a positive reputation with email providers is essential and directly impacts email deliverability. BCC usage can negatively influence this dynamic reputation.
- Engagement as a key metric: Most deliverability guides underscore engagement metrics (opens, clicks, replies) as critical factors. BCC’d emails, typically having zero engagement, will dilute these positive signals.
- Warm-up goals: The purpose of email warm-up, as detailed in documentation, is to establish trust as a valid sender and increase deliverability. BCC practices that introduce unengaged volume run counter to these goals.
- Volume and consistency: Guides often advise maintaining consistent send volumes that align with engagement expectations. BCC can create an artificial increase in volume without corresponding engagement, triggering ISP filters.
Key considerations
- Adhere to best practices: Follow general email deliverability best practices, which emphasize sending relevant content to engaged recipients, and minimize practices like BCC that can obscure true engagement.
- Monitor domain reputation: Understand that various factors influence your domain's reputation, including engagement rates and spam complaint rates. Unopened BCCs can contribute to a poor perceived engagement rate.
- IP warming strategy: Integrate a clear IP warming strategy that accounts for all email volume, including any necessary BCCs, ensuring it doesn't skew the positive engagement curve you aim to achieve.
- Automated warming limitations: While email domain warming is essential, automated warm-up services might not account for unengaged BCC volume, requiring manual oversight to prevent reputation issues.
Technical article
Documentation from EngageBay states that ISPs look at your sender reputation to determine email deliverability. Your reputation is comprised of factors like engagement, and an abundance of unengaged BCC’d emails can severely damage this.
Technical article
User Guide from MoEngage highlights that email domain warming is crucial for establishing a positive reputation with email providers, which directly influences deliverability. Practices that introduce unengaged mail (like BCC) work against this fundamental objective.
Related resources
11 resources
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