Cost optimization

Most ESPs charge per contact or per email sent. Sending to unengaged contacts inflates your costs without generating revenue — and actively harms your deliverability by dragging down engagement rates. InboxEagle’s cost optimization tool identifies these contacts and recommends suppression strategies to reduce ESP costs by an average of 40%, with zero revenue impact.

How it works

The cost optimization tool layers three data sources to identify unengaged contacts:

1. Bot-filtered engagement from Bot Finder — Raw open rates include bot opens from email security scanners and privacy proxies. Bot Finder filters these out, so InboxEagle works with confirmed human engagement signals only. A contact who has only “opened” via a bot has never actually engaged.

2. Recency and frequency from Klaviyo or SES — When was the last confirmed human open or click? How often has this contact engaged versus received emails? Contacts who have received dozens of emails over 6+ months without a single confirmed human engagement are strong suppression candidates.

3. Inbox placement signals — Contacts at providers with high spam placement rates may be abandoned addresses. If mail to a particular domain cluster is consistently going to spam, those addresses are unlikely to ever engage.

The result is a ranked list of contacts flagged for suppression, with the expected cost and deliverability impact of suppressing each group.

Suppression strategies

Sunset policy

A sunset policy suppresses contacts who have not shown confirmed human engagement within a defined window. InboxEagle recommends a 90–180 day window using Bot Finder-confirmed human opens, not raw open data.

Using raw opens for suppression decisions is a common mistake — Apple Mail Privacy Protection and corporate email security scanners inflate open rates, making unengaged contacts appear active. With Bot Finder data, your sunset policy is based on actual human engagement.

Recommended approach:

• Suppress contacts with no confirmed human open or click in the past 180 days
• Run a re-engagement campaign first for contacts in the 90–180 day window (see caution below)
• Immediately suppress contacts with no confirmed human engagement ever (all opens were bot opens)

Bot-engagement-only contacts

Some contacts in your list have open history that consists entirely of bot opens — security scanners, privacy proxies, or link prefetchers. They have never had a confirmed human open. These contacts are the highest-confidence suppression candidates because:

• They may be abandoned or role-based addresses where email is pre-scanned but never read
• Any engagement signal they generate is artificial and inflates your metrics
• Suppressing them improves your true engagement rate without removing any real subscribers

InboxEagle identifies these contacts from Bot Finder’s per-event classification data. If every open event for a contact has a bot signal, they appear in this group.

Bounced and undeliverable

Hard bounces and permanently undeliverable addresses that have not been suppressed in your ESP continue to count toward your contact limit at most ESPs. Identifying and suppressing them reduces costs and prevents repeated bounce events that can harm IP and domain reputation.

InboxEagle surfaces addresses that have accumulated bounce signals in your send history data. These should be suppressed immediately — there is no re-engagement path for a hard bounce.

Run a cost optimization analysis

1. Open Cost Optimization

   In the InboxEagle app, navigate to Deliverability → Cost Optimization.

2. Select your connected account

   Choose your connected Klaviyo account or SES Bot Finder instance. InboxEagle will pull engagement data from this source.

3. Choose your suppression criteria

   Set the parameters: last confirmed human engagement date (e.g., no human open in the past 180 days) and whether to include bot-engagement-only contacts.

4. Review the flagged contact list

   InboxEagle shows the number of contacts flagged per group, their current contribution to your ESP bill, and the projected cost reduction from suppression.

5. Export and suppress

   Download the suppression list as a CSV and upload it to your ESP’s suppression list, or sync directly to Klaviyo’s suppression list if you have Klaviyo connected.

Caution

Before suppressing, review the flagged list carefully. Contacts who read email exclusively through Apple Mail will appear as “bot-engagement-only” because Apple Mail Privacy Protection pre-fetches images, triggering open events without user action. These are real subscribers. Consider running a re-engagement campaign (e.g., a plain-text email with a clear click-to-confirm CTA) before final suppression. Only click events can confirm human engagement for Apple Mail users.

Estimating your savings

To calculate your expected cost reduction:

(Flagged contacts ÷ Total contacts) × Current monthly ESP cost = Estimated monthly savings

InboxEagle shows this calculation in the cost optimization dashboard. The average reduction across programs that have never cleaned their list is 40%. Programs that have performed list hygiene within the past year typically see 10–20% reductions.

Suppression and Klaviyo

Once you identify contacts to suppress, you can:

• Upload the CSV to Klaviyo’s Suppression list under Audience → Suppressions
• Use Klaviyo’s bulk unsubscribe feature via the Profiles section
• Sync suppression directly through the Klaviyo integration if it is connected to InboxEagle

Suppressed contacts in Klaviyo will not be emailed, but they remain in your account for record-keeping and GDPR compliance purposes.

Next steps

• Bot Finder — Set up human engagement filtering for accurate suppression decisions
• Klaviyo integration — Connect Klaviyo for engagement data and direct suppression sync
• Improve inbox placement — How list hygiene connects to placement rates

Run cost optimization →