Tomorrow vs. Shortwave: the AI inbox for any email address
Shortwave is one of the best AI email clients around — if you live in Gmail. Tomorrow brings the same kind of AI to any mailbox, and goes further with approval-first automation.
You’re on Outlook, Proton, Fastmail, or a custom domain — or you want an inbox that prepares actions and automations for you, not just faster manual email.
You’re all-in on Gmail and Google Workspace and mainly want a polished AI client for reading and replying inside that one account.
The honest summary
Shortwave is a genuinely good product. It put AI search, summaries, and drafting into a fast Gmail experience, and if Gmail is your whole world it’s an easy recommendation. The catch is right there in that sentence: Gmail. Shortwave is built on the Gmail API, so the moment your email lives on Outlook, Proton, Fastmail, or your own domain, it’s not an option.
Tomorrow starts from the opposite assumption — that email is bigger than one provider — and adds an agentic layer on top: it doesn’t just help you write faster, it prepares the work and waits for your go-ahead.
Feature comparison
| Feature | Tomorrow | Shortwave |
|---|---|---|
| Works on Gmail | Yes | Yes |
| Works on Outlook | Yes | No |
| Custom domains over IMAP/SMTP | Yes | No |
| Proton, Fastmail, any mail server | Yes | No |
| AI-drafted replies in your voice | Yes | Yes |
| Natural-language inbox chat | Yes | Yes |
| Proactively prepares actions | Yes | Reactive |
| Plain-language workflow automation | Yes | No |
| Approval before any action runs | Yes | Yes |
| Connects to outside tools (invoices, tasks) | Yes | No |
Where Tomorrow pulls ahead
It works on any email address. This is the big one. Tomorrow speaks IMAP and SMTP directly, so it connects to Gmail and everything Shortwave can’t — including custom domains. For founders and freelancers on you@yourcompany.com, that’s the difference between having an AI inbox and not.
It’s proactive, not reactive. Shortwave assists when you act — you open a thread, you ask it to draft. Tomorrow reads what comes in, understands the context, and prepares the reply, the follow-up, or the task before you ask — then holds it for your approval.
It automates beyond the inbox. Describe a workflow in plain language — “when a supplier emails an invoice, create it in Moneybird” — and Tomorrow builds the recipe and connects the tool. No Zapier, no flow builder. Shortwave keeps you inside the mail client.
Where Shortwave is still a fine choice
If you’re committed to Gmail and want a fast, well-designed AI client for triage and replies, Shortwave does that well. Tomorrow’s edge shows up when you outgrow Gmail-only, or when you want an assistant that prepares and executes work rather than only speeding up your typing.
Frequently asked questions
What is the best Shortwave alternative?
If you need AI email beyond Gmail, Tomorrow is the closest alternative: it brings AI-drafted replies, inbox chat, and automation to any IMAP mailbox — Outlook, Proton, Fastmail, or a custom domain — which Shortwave does not support.
Does Shortwave work with custom domains or Outlook?
Shortwave is built for Gmail and Google Workspace. It does not connect to Outlook, Proton, Fastmail, or custom domains over IMAP. Tomorrow connects to any of these.
How is Tomorrow different from Shortwave?
Two main differences: Tomorrow works on any email address (not just Gmail), and it is proactive — it prepares replies and sets up automations from plain-language intent, then waits for your approval, rather than only assisting when you ask.
Can I switch from Shortwave to Tomorrow?
Yes. Connect your mailbox — including the same Gmail account — and Tomorrow works on top of it. Your email stays where it is; nothing is migrated or locked in.
The AI inbox that works on any email address
Connect any mailbox — Gmail, Outlook, Fastmail, or a custom domain — and let Tomorrow prepare your replies and automations, with your approval before anything sends.
