How does sending email to inactive contacts affect deliverability?

Key findings

• Reputation Impact: Emailing unengaged contacts can harm your overall sender reputation with ISPs. ISPs monitor engagement metrics closely, and a lack of interaction signals poor list quality.
• Spam Trap Risk: Inactive email addresses, especially those abandoned for a long time, are often converted into spam traps. Hitting a spam trap can severely damage your reputation and lead to blacklisting.
• Spam Complaints: Recipients who no longer remember opting in or are uninterested are more likely to mark your emails as spam, which is a strong negative signal to ISPs.
• Bounce Rates: Old, inactive addresses are prone to becoming invalid, resulting in hard bounces. High hard bounce rates indicate poor list hygiene and can trigger deliverability issues.
• Engagement Metrics: Low open and click-through rates from inactive segments dilute your overall engagement statistics, signaling to ISPs that your content is not relevant or desired by a significant portion of your list.

Key considerations

• Segmentation: Isolating inactive contacts into a separate segment allows for targeted re-engagement strategies or removal, preventing them from negatively impacting your main sending stream. Mailjet suggests that managing inactives prevents emails from being sent to uninterested recipients.
• Definition of Inactive: The definition of an inactive contact can vary. Aggressively marking contacts as inactive (e.g., after one month) might be too soon, as some users genuinely want emails but don't open every one.
• Gradual Re-engagement: If attempting to re-engage, do so with very small volumes mixed into high-engagement streams to mitigate risks, or send dedicated re-engagement campaigns with specific, non-sales objectives.
• List Cleaning: Regularly removing contacts who remain unengaged after re-engagement attempts is crucial for maintaining a healthy list and protecting your sender reputation. For more on this, see how to manage deliverability when re-engaging inactive email subscribers.
• Long-term Impact: While one or two campaigns with low open rates might not immediately tank your deliverability, consistent sending to inactive users over time will lead to worsening inbox placement across the board, even for active recipients. Mailchimp highlights that consistent high engagement helps email clients see you as a trusted sender.

Key opinions

• Volume is Key: It's less about the number of campaigns to inactives and more about the volume of recipients within those campaigns. A small percentage of inactives mixed with engaged senders is less risky.
• Gradual Approach: If re-engaging, spread the volume of messages to inactive contacts over weeks or months, especially for non-time-sensitive content.
• Single Objective: Re-engagement campaigns should have a clear, singular objective, which is often not direct sales performance, but rather regaining engagement.
• Beyond Opens: Defining 'active' solely by opens might be too narrow. Some users might visit your website directly after seeing your email, indicating engagement that isn't tracked via opens or clicks.
• Beware of Aggressive Removal: Aggressively removing contacts as inactive after only a month can be too soon and might be mistaken for spamming behavior by ISPs. Google and Yahoo consider consistent sending to unengaged users as detrimental.

Key considerations

• Risk Mitigation: Aim to keep 'high-risk' recipient mails (e.g., to very inactive addresses) to a very small percentage of your overall sending volume, perhaps less than 1%.
• Strategic Re-introduction: When contacting long-inactive subscribers, carefully re-introduce your brand and explain why you are reaching out again to minimize spam complaints.
• Engagement Cadence: Consider a dynamic frequency policy that slows down mail to recipients whose engagement drops, and increases it if engagement picks up, rather than a binary active/inactive status.
• Impact on Active Users: A large send to contacts who never open your emails may cause wider deliverability issues that can lead to bouncing even with your active audience, as noted by Acoustic.
• Defining Inactivity: An email address is not necessarily 'dead' just because it hasn't engaged in a few months. ISPs don't typically mark an address as truly inactive until someone hasn't logged in for many months. Learn more about the risk of sending email to inactive users.

Key opinions

• Spam Trap Risk is High: Sending to long-inactive addresses carries a major risk of hitting spam traps, which can cause severe damage to sender reputation and lead to blacklisting.
• Spam Complaints are Critical: If recipients do not remember opting in or no longer want mail, they are likely to report it as spam, resulting in a significant negative impact on sender reputation.
• Dead Addresses are a Minor Hit: While mailing dead addresses (those no longer used by the recipient) is a negative hit, it is generally considered less severe than spam complaints or hitting spam traps.
• ISP Definition of Inactive: ISPs typically do not consider an email address 'dead' until a user has not logged into it for many months, often beyond what marketers might define as inactive. Microsoft, for example, might start bouncing mail to inactive addresses after about three months.
• Aggressive Removal Misperception: Dropping addresses too aggressively, such as after only a month of inactivity, can be perceived by some deliverability professionals as a sign of spamming behavior.

Key considerations

• Gradual Volume for Inactives: Minimizing the impact of dead addresses and spam traps can be achieved by sending very low volumes to inactive segments over an extended period.
• Careful Re-introduction: To mitigate spam complaints, carefully re-introduce yourself to long-inactive contacts and clearly explain the reason for contacting them again.
• Historical Context: The advice to clean inactive lists evolved from dealing with senders who mailed contacts opted-in many years ago, not necessarily from a one-month inactivity threshold. For more insights, refer to an expert guide to improving email deliverability.
• Impact on Reputation: A large number of bounces from sending to non-existent or inactive email accounts can definitely reduce your sender reputation, as highlighted by Customer.io.
• Avoid Over-Aggressive Hygiene: While list hygiene is good, excessive or overly aggressive cleaning based on short inactivity periods can be counterproductive and misinterpret genuine, albeit infrequent, engagement patterns. Explore more on how email list quality and sending frequency impact deliverability.

Key findings

• Engagement Signals: ISPs use engagement metrics (opens, clicks, replies, non-complaints) as key indicators of sender reputation. Low engagement from a segment negatively impacts these signals.
• Reputation Degradation: Sending to unengaged recipients, or those who consistently ignore your emails, directly contributes to a decline in sender reputation and can cause wider deliverability issues, as mentioned by Campaign Monitor.
• Spam Complaint Thresholds: Many providers have strict spam complaint thresholds. Inactive contacts are more likely to complain, pushing senders over these limits.
• List Quality Importance: Documentation often stresses that list quality is paramount. Sending to a list with a high percentage of inactive or invalid addresses indicates poor list hygiene.
• Hard Bounce Impact: High numbers of hard bounces from old, inactive addresses signal to ISPs that your list contains many non-existent accounts, negatively affecting deliverability. Customer.io highlights that a large number of bounces can reduce sender reputation.

Key considerations

• Segment and Target: Segment your list by engagement level and send different types of campaigns (or no campaigns) to different segments.
• Re-engagement Best Practices: If attempting to re-engage, use specific re-engagement campaigns with clear calls to action (e.g., 'Click to stay subscribed') rather than regular promotional content. ActiveCampaign suggests removing inactive contacts as continued sending is dangerous.
• Sunset Policy: Implement a clear sunset policy for inactive subscribers, establishing criteria for when contacts are moved to a re-engagement segment and eventually removed from the list if no engagement is recaptured.
• Monitoring Tools: Utilize available postmaster tools (e.g., Google Postmaster Tools) to monitor your sender reputation and identify potential issues arising from sending to inactive users, such as high spam rates. Mailgun advises that sending to inactive or non-existent counts can hurt sender reputation and engagement metrics.
• Regular List Cleaning: Perform regular list hygiene to remove invalid and permanently unengaged email addresses to protect your sender reputation and ensure high inbox rates. This directly supports the principles outlined in our guide to improving domain reputation.