What are sending limits and how are they set in my inboxes?

THIS ARTICLE IS FOR: All ListKit customers
​Stage: Onboarding
​Owner: Said
​Last updated: July 2026
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Sending limits exist to protect your inboxes and your sender reputation. Inbox providers like Google monitor sending behavior closely, an inbox that suddenly sends hundreds of emails per day looks suspicious and gets flagged. Sending limits keep your inboxes inside the range that inbox providers recognize as normal, legitimate behavior.
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This is one of the most important settings in your entire cold email setup. Getting it wrong quietly damages your deliverability before you even notice anything is wrong.
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Each inbox in Email Engine has its own individual daily sending limit. This is the maximum number of emails that inbox will send in a single day, regardless of how many contacts are in your active campaigns.
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ListKit pre-configures this limit for you based on what delivers the best results at scale. The limit is set to keep your inboxes inside the safe sending range that inbox providers recognize as normal, legitimate behavior, while still hitting your daily volume target across your full inbox set.
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Your actual daily send volume may vary slightly depending on other deliverability settings working in the background. This is by design and keeps your infrastructure in the safe operating zone.
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This is not an arbitrary number. It is the result of ListKit having sent more cold email volume than any other platform in the market and knowing exactly where the safe ceiling sits for a warmed inbox sending consistently over time.
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Too low and you are leaving sending capacity on the table. Too high and you start signaling unusual behavior to inbox providers, which leads to emails landing in spam, open rates dropping, and sender reputation taking damage that takes weeks to recover from.
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28 per inbox per day is the number that sits at the optimal point, high enough to hit your volume targets, safe enough to protect your deliverability for the long term.
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Yes, you can update your daily sending limit per inbox from inside Email Engine. Click the three dot menu on any inbox and select Update Daily Sending Limit.
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However, changing this setting is not recommended unless you have a specific reason and experience to back it up. The pre-configured limit is already set to the most efficient level for safe, high-volume sending. Increasing it beyond the default is one of the most common causes of deliverability problems, and the damage is not always immediate, which makes it easy to miss until it is too late.
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If you feel your sending volume is not where it should be and you think your limits might be the cause, reach out to the support team before making any changes. The team will check your setup and advise on the right course of action.
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With sending limits pre-configured at the optimal level across all your inboxes, your campaigns send consistently at your target volume without triggering any flags from inbox providers. Your emails land in the inbox, your open rates stay healthy, and your sender reputation is protected for the long term.
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Why does my total daily sends come out slightly under my target volume?
The sending limit per inbox is one of several deliverability settings working together in the background. Other settings may slightly reduce the total number of sends on any given day, this is by design and keeps your infrastructure in the safe operating zone.
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What happens if I set my sending limit too high?
Inbox providers may flag your sending behavior as unusual, which leads to emails landing in spam or promotions folders. Open rates drop, reply rates follow, and your sender reputation takes damage that can take weeks to recover from. This is why the pre-configured limit exists.
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My inboxes are not sending at the expected volume, is the sending limit the problem?
It could be one of several factors. Reach out to support via Intercom chat or at [email protected] and the team will diagnose your setup and identify the cause.
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Can I set different sending limits on different inboxes?
Yes. The Update Daily Sending Limit option is available per inbox, so you can adjust individual inboxes independently. That said, keeping all inboxes at the same pre-configured default is strongly recommended unless you have a specific reason to change individual ones.