Feature Concept: Running Multiple Versions of Apple Mail (Per-Domain Separation)

[nollimac]

I’m a longtime Apple Mail user and honestly find it hard to replace — even compared to paid alternatives. That said, I’ve run into a real-world limitation I’d love Apple to consider addressing in a future macOS release:

Apple Mail is sandboxed, which I get. But what if we had the ability to run multiple isolated instances of Mail, each tied to a specific domain or business use case?

Example:

• Mail (default) → domainA.com
• Mail1 → domainB.com
• Mail2 → domainC.com

Each version would operate independently — with its own settings, accounts, signature files, and mailboxes. This would eliminate the noise and confusion of switching between identities in one unified app.

It’s not about complexity — it’s about clarity. With so many people juggling multiple roles (personal, nonprofit, business), it makes sense to segment communication environments without relying on 3rd-party apps like Outlook, Thunderbird, Airmail, etc.

Curious if others feel the same or have found clever workarounds. Is this something worth pushing as a feature request for macOS 26 or beyond?

 

[adrianlondon]

I guess it could be done now via multiple OS users and fast-user switching.

Focus modes can also be used to enable a set of accounts (with the rest de-activated). You could also use it to switch calendars (and, of course, tailor notifications).

Not as neat as your idea, though.

 

[nollimac]

I guess it could be done now via multiple OS users and fast-user switching.

Focus modes can also be used to enable a set of accounts (with the rest de-activated). You could also use it to switch calendars (and, of course, tailor notifications).

Not as neat as your idea, though.

Sure, you can work around it using Focus modes or Fast User Switching, but that still doesn’t solve the core issue — Apple Mail doesn’t support fully isolated account instances. That forces users to either micromanage toggles or resort to third-party apps — often with high subscription costs — just to keep work, nonprofit, and personal domains separate.


It’s not about features — it’s about workflow dignity. Especially for users managing multiple domains. That’s the real power user Apple keeps overlooking.

 

[nollimac]

Why Signatures and Sovereign Identity Call for Isolated Apple Mail Instances​

Most users don’t think much about email signatures — but for those managing multiple domains or roles, signatures are more than a footer.
They’re legal markers, brand identifiers, and signals of trust.
When you're running a nonprofit, a personal brand, and maybe a side business — all on different domains — your signature isn’t just text. It’s an extension of your sovereign digital identity.
Today, Apple Mail treats every account as if it's part of one blurred workspace. There's no native separation of identities, no per-domain instance logic, and no role-aware signature control.
Power users like us are forced to rely on third-party apps, multiple devices, or risky workarounds — just to keep personal emails from going out with foundation signatures, or legal disclaimers from crossing wires.
This isn’t about features.
It’s about workflow dignity — and respect for digital identity in a multi-domain world.
And it was this exact need — managing signatures with sovereign ID across domains — that shaped the call for multi-instance Apple Mail.
To make Mail not just smarter… but simpler and more powerful.