Mailing Lists Are Now Built Into KaiMail

If you've ever needed to run a simple mailing list — announcements to a team, newsletters to subscribers, or a small discussion group — you've probably reached for a separate tool. Mailchimp for broadcasts, Google Groups for discussions, some other SaaS glued on the side. Each one means another login, another monthly bill, and another thing to maintain.

KaiMail now has mailing lists built in, using your own custom domain.

Three Types of Lists

When you create a List mailbox on any of your custom domains, you choose one of three modes:

Public (default)

Any email sent to the list address is forwarded to all members. No sender restrictions. This is the original KaiMail list behaviour — a simple multi-address forward that "just works". Anyone who emails the list gets through.

You'll usually use this type of list for a shared mailbox, e.g. [email protected] for a three-person sales team.

Broadcast

Only the list owner can post, via authenticated SMTP (port 587). Inbound emails from anyone else are rejected with a clear bounce message. Use this for newsletters and announcements where you want full control over who can send.

For example, we use this type of list for event announcements. We have a community that is interested in Python conferences, so they sign up and we send out periodic emails to announce conference dates and Call for Proposal (CfP) deadlines.

Discussion

Members can reply-all and the conversation stays on the list. Posts are validated for DMARC alignment and active membership before delivery — only confirmed members can post. Emails sent to the list have their Reply-To header set to the list address so replies flow back through the list rather than going directly to the original sender.

How It Works Under the Hood

Every email sent through a broadcast or discussion list is DKIM-signed with your list domain's key, not the original sender's. This means authentication passes correctly for all list recipients, and your messages land in inboxes rather than spam folders.

For broadcast lists, you compose the email in your regular mail client and send it through KaiMail's port-587 SMTP submission. KaiMail rewrites the From: header in a DMARC-compatible way (similar to how Mailman handles it), signs the message with your domain key, and fans it out to all subscribers.

Setting It Up

1. Log in to your KaiMail dashboard and open any of your custom domains.
2. Add a new mailbox and choose Email List as the route type.
3. Select the list type: Public, Broadcast, or Discussion.
4. Add subscriber addresses to the list.

That's it. Emails sent to the list address are handled according to the mode you selected.

Plan Availability

Mailing lists are available on all plans, but Broadcast and Discussion modes require a paid plan (Plus, Pro, or Business). Basic plan users can create Public lists only.

Broadcast and Discussion modes are bundled with SMTP sending — both are included on all paid plans.

Why This Matters

Running a mailing list on your own domain means your subscribers see emails from [email protected], not from some third-party sending service. SPF, DKIM, and DMARC all align properly because KaiMail controls the full sending path. You're not paying a separate per-subscriber fee just to send a monthly update to a few dozen people.

If you're already using KaiMail for forwarding, lists are just another mailbox type on the same domain you already manage.

Mailing lists are live now. Log in to your dashboard to get started.

Also For Your Reading Pleasure

• Read too about how we wrangled with DKIM to make the Reply-To work for our mailing lists.