If you've landed here, you've probably already tried Missive and felt a small mismatch you couldn't quite name. The tool is good. It's well built and people who use it for the right job genuinely love it. But something about it doesn't sit right for the way you work, and it's worth being precise about what that something is before you go looking for a replacement.
The short version: Missive is a team tool. If you're one person running several businesses, you may be reaching for software shaped around a problem you don't have, and missing the one you do.
Missive is a shared-inbox and team-collaboration product. Its core idea is that several people work the same mailboxes together: assigning conversations, leaving internal comments next to a thread, drafting replies as a team, and avoiding two people answering the same customer. For a support desk, a sales team, or a small company where a few people share support@ and hello@, that's a strong fit and the collaboration features are the whole point.
If that describes your situation, Missive is probably right for you, and this article isn't trying to talk you out of it. The mismatch shows up for a different person.
The friction appears when the person using it isn't a team, but a single operator wearing many hats. A founder with an agency, a SaaS, and a side project doesn't need to assign conversations to teammates or comment internally on a thread. There are no teammates. The job isn't collaboration. The job is separation.
Three things tend to grate, in that case.
You're paying for collaboration you don't use. A meaningful share of Missive's value, and its per-user pricing model, is built around team workflows. As a solo operator, you're carrying the weight of features designed for a use case that isn't yours.
Separation by business isn't the organizing principle. Missive organizes around shared inboxes and team assignment. Keeping three businesses in three genuinely distinct, non-bleeding contexts, where the right sending identity is automatic per business, is something you assemble rather than something the tool is centered on.
It's a closed, hosted product. Your mail flows through their service and you can't self-host or read the source. For some people that's fine. For founders who care about controlling where their mail lives, it's a hard line.
If the team features are the part you don't need, the questions that actually matter for a multi-business operator are different ones.
Does it organize by business, not by account or by assignee? The unit that matters to you is the business an email belongs to. The right tool sorts on that, automatically, by the address the mail was sent to.
Is the right identity automatic? When you reply inside a given business, it should go out as that business without you choosing a From address. The most common multi-business mistake is replying as the wrong identity, and the fix is structural, not a reminder to be careful.
Can you see everything at once without it merging? Separation can't mean checking five places. You want all your businesses visible on one screen, each in its own lane.
Do you control where your mail lives? Whether through self-hosting or open source, the option to own the infrastructure is worth real money to some founders and worth nothing to others. Know which you are.
Cereal is built for the person Missive isn't built for: one operator running more than one thing. Instead of shared inboxes and team assignment, the organizing principle is the business itself. Each business gets its own bowl. Mail routes into the right bowl by the address it was sent to, so the sorting happens on its own. You see every business at a glance on one screen without the streams blending, and when you reply, your identity is set by the bowl you're in, so the wrong-sender mistake stops being possible.
It connects to mailboxes you already own, any IMAP or SMTP provider plus Gmail, Workspace, and Outlook, so you're not migrating your mail anywhere. And it's open source under AGPL, so you can self-host it and read exactly what it does with your email, which is a different posture from a closed hosted service.
The honest summary: if you need a team to work a shared inbox together, use Missive. If you're one person who needs several businesses to stay cleanly separate with the right identity every time, that's the exact problem Cereal was built for. We go deeper on the underlying setup in our guide to managing email across multiple businesses.
Pick the tool shaped like your problem. If your problem is separation rather than collaboration, you've been using the team version of an answer to a solo question.