A common assumption: since Mailchimp is a big, reputable platform, it must handle deliverability for you. It doesn't — not for your own sending domain. Mailchimp's infrastructure is trusted, but the domain your campaigns actually send from still needs to earn its own reputation with inbox providers, especially if it's new or hasn't sent much volume yet. That's where domain warmup comes in, and because Mailchimp doesn't offer SMTP or IMAP access, the usual mailbox-connection warmup isn't an option here — you need E-Warmup's Seedlist Warmup instead, run through Mailchimp's own campaign tool.
Mailchimp doesn't offer SMTP or IMAP access, so a normal warmup connection isn't possible on this platform. Seedlist Warmup solves that: instead of connecting your mailbox, you add E-Warmup's seed addresses as an audience inside Mailchimp and send to them from a Mailchimp campaign. Our network engages with those emails the same way it does with a connected mailbox, and your sending domain's reputation builds normally — so by the time you're sending real campaigns, your domain is already trusted by inbox providers.
This guide walks you through warming up a Mailchimp sending domain with Seedlist Warmup, start to finish.
Prerequisites
An active E-Warmup account
Seed credits (purchase from the dashboard )
Access to your Mailchimp account, with the sending domain you want to warm up already verified in Mailchimp
Log in to your E-Warmup dashboard and open the Seedlist Warmup section from the left navbar.
Select a pack that matches your needs:
Warmup Launch – 200 credits ($19 one-time)
Warmup Campaign – 600 credits ($37 one-time)
Warmup Session – 1,000 credits ($55 one-time)
Or contact us for a DFY / custom pack
Credits never expire and can be used across unlimited campaigns. Not sure which pack to choose? Contact live chat support and we'll help you size it to your sending volume.
Sender Address – Enter the exact "from" email address you'll use to send the campaign from Mailchimp (this should be on the domain you're warming up).
Download the seed list – Download the latest seed list (CSV). Lists are mixed across Gmail, Outlook, and Yahoo and support both B2B and B2C orientations. Always download a fresh list before a new campaign.
Import the seed list into Mailchimp – In Mailchimp, go to Audience → Audience dashboard → Import contacts, and import the CSV as a new audience (or a tagged segment inside an existing audience). This becomes the recipient list for your warmup campaign.
Set up tracking – Copy the unique tracking code from the Tracking setup box. In Mailchimp's campaign builder, paste this code into the subject line of the email you're sending to the seed list. This is how E-Warmup detects when your emails reach the seed addresses. After adding the code, check the box: "I've added the tracking code to my mail subject line."
In Mailchimp, create a campaign, set the recipients to the seed audience/segment you just imported, and send or schedule it as normal. Then return to your E-Warmup Seedlist Warmup campaign, click Start Warmup, and select when the seed warmup system should begin.
Note: Send this campaign only to the seed list you imported — not to your real subscribers.
Return to your E-Warmup campaign page to track engagement and inbox placement as the seeds start interacting with your emails.
Things worth double-checking:
The sender address matches the warmed-up domain exactly
The seed audience stays separate from real subscribers, permanently
The tracking code is still in the subject line at send time
Seed volume ramps up gradually rather than jumping straight to a large send
Can you warm up a domain in Mailchimp without SMTP access?
Yes. Mailchimp doesn't support SMTP/IMAP mailbox connections, so E-Warmup uses Seedlist Warmup instead — you send to a seed audience from inside Mailchimp, and E-Warmup's network handles the engagement that builds domain reputation.
How long does Mailchimp domain warmup take?
Warmup timelines depend on your current sending volume and domain age, but most users start with a smaller seed list and scale up gradually over several weeks, as noted in the Quick tips above.
Does Seedlist Warmup work for other platforms without SMTP, like Klaviyo or Shopify?
Yes — the same seed-list method works for any ESP that doesn't expose SMTP/IMAP, including Klaviyo, Omnisend, HubSpot, and Shopify.
Where do I get the tracking code for my Mailchimp campaign?
It's shown in the Tracking setup box in your E-Warmup Seedlist Warmup campaign — copy it into the subject line of the Mailchimp email you send to your seed audience.
Doesn't Mailchimp already have a good sender reputation I can rely on?
Mailchimp's platform-level infrastructure is well-established, but that's separate from your specific sending domain's reputation, which inbox providers evaluate independently based on how that domain has been used.
Do I need a paid Mailchimp plan to use Seedlist Warmup?
Seedlist Warmup works through whatever Mailchimp plan lets you create and send a campaign to an imported audience — check Mailchimp's own plan limits for audience size and sending volume.
Will warmup affect my existing Mailchimp subscribers?
No, as long as the seed list stays in its own separate audience or segment and the warmup campaign is only sent there — your real subscribers are never included.
Need more details about Seedlist Warmup? Check this article: Introducing Seedlist Warmup for Mailchimp, Klaviyo, Omnisend, Shopify, and any ESP that doesn't support SMTP.
Introducing Seedlist Warmup
Warmup for Mailchimp, Klaviyo, Omnisend, Shopify, and any ESP that doesn’t support SMTP
