Unibox had one good idea and built an entire client around it: stop organizing email by folder, organize it by person. Every conversation with someone becomes one thread, iMessage-style, regardless of subject line. It is a clean idea and it still works well for a lot of people.
Because STAMP also groups mail into something closer to conversations than folders, we get asked how the two compare more than you would think. Here is the honest answer.
What Unibox is, in one sentence
Unibox is a macOS and iOS email client that replaces the folder-and-subject model with a person-centric conversation view, all your mail with one contact in a single thread, chat-style.
If your inbox problem is mainly "I can never find the last thing this person said," Unibox solves that directly.
What STAMP is, in one sentence
STAMP is a triage-first client that ranks what needs a reply today across every account, using on-device classification to score urgency, VIP status, and follow-up need, not just group by sender.
The overlap is real: both reject the classic folder-and-subject inbox. The difference is what replaces it.
The bets, side by side
| Dimension | Unibox | STAMP |
|---|---|---|
| Primary bet | Group by person removes the folder problem | Rank by urgency removes the "what matters today" problem |
| Main view | Conversations grouped by contact | Threads ranked by what needs a reply today |
| Classification | None, grouping is structural not evaluative | On-device urgency, VIP, and follow-up scoring |
| Account types | Gmail, Outlook, iCloud, IMAP | Gmail, Workspace, Outlook, 365, iCloud, Fastmail, Proton Bridge, IMAP/SMTP |
| Newsletter handling | Grouped like any other sender | Quarantined into a separate reading queue |
| Pricing | One-time purchase | $9/month, $79/year, $199 lifetime |
Where Unibox wins
Three places Unibox is genuinely good at what it does.
- Relationship continuity. If you email the same 30 people repeatedly, seeing the full history with each one in a single thread is genuinely useful and STAMP does not organize mail this way.
- Simplicity of the idea. Unibox does one thing and does it without much else getting in the way. There is a real appeal in that restraint.
- One-time pricing. No subscription. For someone who wants to pay once and be done, that is a real advantage over STAMP's model.
If those three matter most to you, Unibox is the right choice today.
Where STAMP wins
Three places we are confident we are better.
- Urgency, not just grouping. Grouping by person tells you who emailed you. It does not tell you which of those 30 people need a reply today versus which can wait. STAMP scores that directly.
- On-device privacy with active classification. STAMP's ranking runs locally and nothing leaves your Mac. Grouping by sender is structural, so there is less to protect, but there is also less being done for you.
- Newsletter and noise handling. Unibox still threads a newsletter into the same view as a client email if you happen to reply to it once. STAMP separates promotional and low-priority mail into its own queue automatically.
What we won't pretend
Person-grouping and urgency-ranking are not mutually exclusive ideas, and Unibox got to the "stop organizing by folder" insight early. If your actual daily pain is losing context in long-running relationships rather than not knowing what is urgent, Unibox's model may map to your problem more directly than STAMP's does.
A simple test
Think about your last stressful email morning. Was the problem "I couldn't remember what Sarah and I discussed last week," or was it "I had 60 unread messages and no idea which ones actually needed me today"? The first is a Unibox problem. The second is a STAMP problem.
Who should pick which
Pick Unibox if your inbox is mostly ongoing relationships with a stable set of people and losing thread context is your real pain point.
Pick STAMP if you are dealing with volume across multiple accounts and the real question every morning is which threads actually need a reply today.
Where to go from here
See what has shipped recently on the changelog, or check pricing and the founding window.
See for yourself. hello@stamp.email