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What are ListKit's pre-warmed inboxes and how do I set them up?

Written by Andre Haykal Jr

TL;DR

  • ListKit's pre-warmed inboxes are domains and inboxes that have already been registered and warmed up, ready to send from in minutes, not weeks

  • They are the recommended option when setting up your bundle, select them during the domain setup step

  • 2.5x higher reply rate and 3.6x more positive replies per 10,000 emails sent compared to self-configured branded domain inboxes

  • 88% of clients who ran both saw better results with ListKit's pre-warmed inboxes

  • No warmup period, send your first email in as little as 5 to 10 minutes after setup, sending still ramps up over 7 days (1 email per day, increasing by 4 per day, up to 25) to protect deliverability
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Video guide:


What are pre-warmed inboxes?

When you set up cold email infrastructure the traditional way, you register new domains, configure DNS records, and then wait for your inboxes to warm up before you can send a single campaign. That is about 2 to 3 weeks before your first campaign email (up to 72 hours to register domains and start warmup, then 14 days of warmup), plus another week to reach full volume.
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ListKit's pre-warmed inboxes eliminate the warmup wait.
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These are domains and inboxes that ListKit has already registered, configured, and warmed up in advance, pulled from a managed pool of ready-to-send infrastructure. When you claim them during your bundle setup, they are attached to your account and ready to send from in minutes.
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This is the recommended option for all new bundle setups and for anyone who wants to start sending as quickly as possible.
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How to set up ListKit's pre-warmed inboxes

Step 1: Go to your Billing page

Click your initials at the bottom left of your ListKit dashboard and select Billing from the menu.
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Step 2: Click Setup Now

Scroll down to the Bundle Setup section and click Setup Now next to your bundle.
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Step 3: Click Confirm and Pick Domains

A setup confirmation screen will appear showing what is included, for example 20 domains and 40 inboxes on the 1,000 emails per day tier, at no extra charge. Click Confirm and Pick Domains to continue.
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Step 4: Select Use pre-warmed domains and inboxes

On the domains page you will see two options:
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Use pre-warmed domains and inboxes (Recommended)
Claim domains from ListKit's pool that have already been registered and warmed up. Both the domains and their inboxes are ready to send from immediately. Send your first email in 5 to 10 minutes, sending volume then ramps up over 7 days (starting at 1 email per day and increasing by 4 per day until reaching 25) to keep deliverability healthy.
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Generate new domains
Register brand new domains for your keyword. These still require the standard warmup period before sending. Send your first email in about 2 to 3 weeks (14 days of warmup, after up to 72 hours to register domains and start warmup).
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Select Use pre-warmed domains and inboxes and click Continue.
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Step 5: Select your pre-warmed domains

A list of available pre-warmed domains will load, each showing Available and Warmed status. Click Auto-select to let ListKit pick the right number of domains for your tier automatically, or browse and select them manually.
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Step 6: Add your website redirect URL

Enter your main company website. This is where prospects will be redirected if they visit one of your sending domains directly.
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Click Continue to Personas.
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Step 7: Set up your sender personas

Add two sender personas, a first name, last name, and inbox username for each. These are the names that will appear in the From field of your emails.
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For each persona, click Assign Domains and select all available domains. Click Save Assignment.
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Once both personas have all domains assigned, click Continue to Checkout.
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Step 8: Confirm your setup

Review your order summary and click Confirm. ListKit will begin attaching your pre-warmed domains and inboxes to your account.
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Step 9: Your pre-warmed domains are claimed

A confirmation screen will appear showing all the domains attached to your account. Click Go to my Inboxes. Your inboxes will appear on the Inboxes page (left sidebar) within a few minutes and are ready to use immediately.


How pre-warmed inboxes compare to setting up your own

ListKit analyzed every campaign run through its platform and compared two groups:
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ListKit's pre-warmed inboxes: domains and inboxes provisioned, warmed, and managed by ListKit.
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Self-configured branded domain inboxes: inboxes that customers set up themselves on their own domains and connected independently. This comparison is against inboxes customers built and connected themselves, not ListKit's Generate new domains option.
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The numbers

Across over 1.7 million classified sends, the difference is decisive:

2.5x higher reply rate
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ListKit's pre-warmed inboxes achieved a 0.848% reply rate vs. 0.336% on self-configured branded domain inboxes.
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3.6x more positive replies per 10,000 emails sent
4.7 genuinely interested replies per 10,000 sent on ListKit's pre-warmed inboxes vs. 1.3 on self-configured branded domain inboxes, the number that turns into booked meetings and pipeline.
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88% of clients who tried both saw better results with ListKit's pre-warmed inboxes
In a head-to-head test across 68 clients running the same offer to the same audience, ListKit's pre-warmed inboxes delivered a higher reply rate for 60 of them.
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The math is simple, more positive replies means more meetings booked, more pipeline, and more closed deals. Everything else in a cold email campaign stays the same. The inbox is the only variable that changes.
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What about the bounce rate?

ListKit's pre-warmed inboxes run a higher bounce rate of 4.43% compared to 0.61% on self-configured branded domain inboxes. This is real, expected, and worth understanding.
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Pre-warmed inboxes run on newer domains. Self-configured branded domain inboxes are typically on established domains with years of sending history, which naturally produces a lower bounce rate. Two things keep this firmly in the safe zone:
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It stays under the danger line.
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The cold email industry threshold for a problematic bounce rate is 5%. At 4.43%, ListKit's pre-warmed inboxes stay comfortably under that line. Triple verification at export, warmup and inbox rotation all help keep it there. If a campaign's positive replies start to fall, check its bounce rate and list quality. See Why is my bounce rate high? Here's how to fix it.
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Your primary domain is never touched.
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All sending volume runs on separate infrastructure, not your main business domain. Your company email and website domain are never at risk from cold email sending activity.
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The higher bounce rate is a known and managed characteristic of fresh infrastructure, not a sign of a problem.
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What this means in practice

If you are new to cold email, pre-warmed inboxes remove the single biggest barrier to getting started: the wait. No warmup period and no technical configuration, just a short automatic ramp-up. You claim your domains, set up your personas, and you are ready to send within minutes of completing setup.
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If you have done cold email before and are used to running inboxes on your own branded domains, the data is clear: 88% of clients who tried both got better results with pre-warmed inboxes. ListKit's pre-warmed inboxes produce more replies, more positive replies, and more pipeline. Not slightly more. Meaningfully more.
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​The 7-day ramp-up still applies

Skipping the multi-week warmup does not mean you send at full volume on day one. Pre-warmed inboxes still follow the same 7-day ramp-up schedule as any other inbox, starting at 1 email per day and increasing by 4 emails per day until reaching the full limit of 25 emails per day.
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This is what "send your first email in 5 to 10 minutes" actually means: you can start sending immediately, just at a low volume that increases daily. It is not a shortcut to full-volume sending on day one, it is a shortcut past the multi-week warmup wait.
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While ramping, each inbox's daily limit is locked and rises by 4 per day until it reaches 25. You can see today's limit on the Inboxes page. A low Warm-Up Reputation Score does not mean your inboxes are burned. See What is the Warm-Up Reputation Score and should I worry about it?
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Expected outcome

After completing setup with pre-warmed inboxes, your domains are attached, your inboxes are active, and you can launch your first campaign within minutes, starting at a low daily volume that ramps up to full sending capacity over 7 days. No warmup wait. Just a fast, controlled start.
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Frequently asked questions

Can I get pre-warmed inboxes if I already have a bundle set up with branded domains?

Pre-warmed inboxes are available when setting up a new bundle. If you already have a bundle set up with branded domains, you would need to add a new bundle to access the pre-warmed option. See How do I upgrade my Bundles sending volume?. Reach out to [email protected] if you have questions about your specific situation.

Why do ListKit's pre-warmed inboxes have a higher bounce rate?

They run on newer domains. New inboxes with less sending history naturally produce a higher bounce rate than established branded domain inboxes, but the rate stays within the safe operating band and never affects your primary business domain.

Is this data from real ListKit customers?

Yes. This analysis was pulled from all live and completed campaigns run through the ListKit platform, real clients, real sends, real outcomes. It is not a third party benchmark.

What if I have branded domain inboxes with a strong sender reputation?

Reach out to the support team at [email protected] and they will advise you on the best approach for your specific situation.

Do ListKit's pre-warmed inboxes protect my main business domain?

Yes. All sending volume runs on separate infrastructure, never your primary business domain. Your company email and website domain are never at risk.

What if I want to use my own branded domains instead?

You can select Generate new domains during the setup flow. Note that new domains require 14 days of warmup, plus up to 72 hours to register domains and start warmup (about 2 to 3 weeks from signup), and then a 7-day ramp-up before reaching full sending volume.

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