Tomorrow vs. Spark Mail: a polished client, or an AI agent
Spark is a polished, multi-account email client with AI add-ons and great team features. Tomorrow is a full IMAP client too — but built around a deeper AI agent that prepares and automates your email, with your approval.
You want an AI agent that prepares actions and automates workflows across any IMAP mailbox, with full control over every send.
You want a polished, multi-account client and your priority is team collaboration — shared inboxes, comments, and delegation.
The honest summary
Spark, by Readdle, is a well-built email client. It handles multiple accounts cleanly across platforms, has a tidy “smart inbox,” layers in AI compose and summaries, and is genuinely strong on team collaboration — shared inboxes, comments, and delegation. If those team features are what you need, Spark does them well.
Tomorrow is a full client too, but the center of gravity is different. Spark’s AI helps you write; Tomorrow’s agent does the work — preparing replies and follow-ups before you ask, and automating multi-step tasks from a plain-language description — with an approval gate on everything that leaves your inbox.
Feature comparison
| Feature | Tomorrow | Spark Mail |
|---|---|---|
| Full email client (not a digest/concierge) | Yes | Yes |
| Native IMAP — any provider, custom domains | Yes | Yes |
| Mail stays on your own server, no lock-in | Yes | Synced via Spark |
| AI compose, rewrite & summarize | Yes | Yes |
| Proactive agent that prepares actions for you | Yes | No |
| Plain-language workflow automation | Yes | No |
| Acts in outside tools (invoices, tasks) | Yes | No |
| Approval gate on every agent action | Yes | No |
| Team shared inbox & comments | No | Yes |
Where Tomorrow pulls ahead
From AI features to an AI agent. Compose and summarize are useful, but they’re still you driving. Tomorrow prepares the reply, flags the threads that matter, chases the ones that go quiet, and can act on your behalf once you approve.
Real automation, no flow builder. Describe what you want in plain language and Tomorrow builds the recipe and connects the tool — from 1000+ integrations, plus any tool with an API or a browser fallback. It reaches well beyond what an email client alone can do.
Privacy-first and portable. Your mailbox stays on your own server over standard IMAP/SMTP, with no lock-in — here’s exactly how it connects.
Where Spark Mail is still a fine choice
If your team works out of shared inboxes and you want polished collaboration with AI writing on top, Spark is a strong option. Tomorrow is the better fit when you want an AI agent that prepares and automates the work across any mailbox — and when keeping your mail on your own server matters.
Frequently asked questions
What is the best Spark Mail alternative with AI automation?
Tomorrow is a strong Spark Mail alternative if you want agentic AI, not just writing add-ons. Both are full multi-account clients on IMAP, but Tomorrow proactively prepares actions and automates workflows from plain language, with every action approval-gated.
Is Tomorrow as polished a client as Spark?
Tomorrow is a full, fast email client built for power users. Spark is known for polish and team collaboration features like shared inboxes and comments; Tomorrow focuses on the depth of its AI agent and automation rather than team-inbox collaboration.
How is Tomorrow different from Spark Mail?
Spark offers AI compose, rewrite, and summaries inside a polished multi-account client. Tomorrow adds an AI agent that prepares replies and follow-ups before you ask, automates multi-step workflows, and can act in outside tools — all gated behind your approval.
Does Tomorrow lock me in or move my mailbox?
No. Tomorrow connects over standard IMAP/SMTP and your mail stays on your own server. There is no proprietary mailbox to migrate to and no lock-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.
