Comparison
SlyReply vs every other AI email assistant
Every AI email tool on the market works the same way: it connects to your mailbox. You sign in with Google or Microsoft, grant an app permission to read, compose, send and delete your mail, and the assistant works from inside your inbox. SlyReply is the one that doesn’t. You email an AI agent at its own address and it emails a reply back — no consent screen, no extension, no standing access to anything. This page shows the whole category side by side, states exactly what each claim is based on, and is honest about when a competitor is the better choice.
How to read this
The question isn’t whose AI is smarter. It’s how much it can reach.
Everyone rents the same models — the frontier labs sell to all of us. What actually differs between these products is the permission each one holds while it works. So the comparison below asks one question of each: assume the worst day — a bad model update, a prompt injection hidden in an email it reads, a compromised vendor — how much of your mail is within its reach?
That’s a question about architecture, not about anyone’s good faith. We make no claim on this page about what any vendor stores, trains on, or does with the access it holds — only about what the access permits.
The market at a glance
Access models verified from each vendor’s public documentation, July 2026.
| Product | Exposed on a bad day | |
|---|---|---|
| Fyxer AIInbox-integrated assistantFull mailbox access | Extension / connected account | Every email you have |
| SuperhumanEmail clientFull mailbox access | App | Every email you have |
| ShortwaveEmail clientFull mailbox access | App | Every email you have |
| GmeliusInbox-integrated workflow toolFull mailbox access | Extension / connected account | Every email you have |
| Microsoft CopilotPlatform assistantEverything — it is the platform | Built into Microsoft 365 | Your whole account |
| Google GeminiPlatform assistantEverything — it is the platform | Built into Google Workspace | Your whole account |
| SlyReplyEmail-native assistantNone. You email it. | Nothing | Only what you sent it |
Feature by feature
Compared against the inbox-integrated category rather than vendor by vendor: these rows follow from how a connected assistant has to work, so they hold for all of them — where individual products differ, it’s in features, not in the access model.
| SlyReply | Inbox-integrated tools | |
|---|---|---|
| Needs access to your mailbox | No | Yes |
| OAuth consent screen to grant | None — there isn’t one | Yes |
| Something to install | Nothing | App or extension |
| Can send mail as you | No — it only replies to you | Yes |
| Reach if it misbehaves | The one email you sent | The whole mailbox |
| Works in any email client | Yes | Only the ones it supports |
| Choice of AI model | Anthropic, OpenAI, Stability | Whatever the vendor ships |
| Revoking access | Nothing to revoke — stop emailing it | Revoke the OAuth grant |
The other side
When one of the others is the better choice
You want your inbox managed
Auto-triage, sorting, snoozing, one-click drafts on mail as it lands. That work has to happen inside the mailbox, which means access is the price of entry. Superhuman and Shortwave are built for exactly this and are good at it. SlyReply doesn’t do it and isn’t trying to.
You want AI across your whole workspace
If you want one assistant that spans mail, documents, calendar and files, Copilot and Gemini already live there. That reach is the product. It’s the opposite trade-off to ours, and for some teams it’s the right one.
SlyReply is for the other job: getting expert AI work done over plain email, on any device, without handing anything the keys. Plenty of people use both.
Frequently asked questions
- What is the actual difference between SlyReply and tools like Fyxer, Superhuman or Shortwave?
- Where the assistant sits. Those tools connect to your mailbox — you grant an OAuth permission to read, compose, send and delete your mail, and the assistant then works from inside your inbox. SlyReply sits outside it: you email an AI agent at its own address and it emails a reply back. It is never granted access to your mailbox, so there is no consent screen, nothing to install and nothing to revoke.
- Is SlyReply actually safer, or is that just marketing?
- It is a structural difference rather than a policy one. Every AI assistant can misbehave — a bad model update, a prompt injection hidden in an email it reads, a compromised vendor. What differs is the blast radius. An inbox-integrated assistant holds standing access to your entire mailbox, so that is what is exposed. SlyReply only ever receives the single message you chose to send it, so that is the most it can reach. We are not claiming better intentions; we are claiming less access.
- Do the big platform assistants count?
- Microsoft Copilot and Google Gemini are the most deeply integrated of all — they are part of the platform your mail already lives in, so they can reach not just your mailbox but your documents, calendar and files. That is genuinely useful, and it is the opposite trade-off to the one SlyReply makes.
- When is an inbox-integrated tool the better choice?
- When the job is managing the inbox itself. If you want auto-triage, sorting, snoozing and one-click drafts on the mail already arriving, a connected client is built for exactly that and does it well. SlyReply does not triage your inbox and is not trying to. Plenty of people use both.
- Can SlyReply email my customers for me?
- No. It only ever replies to the address that emailed it, which is yours. If you want a draft to reach a customer you forward it yourself — the send button never leaves your hands.
- What does SlyReply cost compared to the others?
- SlyReply is flat-rate with a free tier and no per-message charges. Competitor pricing changes often enough that quoting it here would go stale, so we link to each vendor's own pricing page instead and keep ours on the pricing page.
Check it yourself. It takes one email.
No account, no card, no consent screen. Send anything to the demo address and watch a reply land in your inbox.
demo@slyreply.aiWant the deeper treatment of the no-inbox-access angle? Read the full write-up →
Sources (July 2026):Fyxer AI · Superhuman · Shortwave · Gmelius · Microsoft Copilot · Google Gemini
Methodology. Every claim above describes what a product’s access model permits, and is verifiable from that vendor’s own public documentation. We make no claim about what any vendor stores, trains on, or does with the access it holds — that isn’t publicly verifiable, so it isn’t asserted. Pricing is deliberately omitted: it changes often enough that a figure quoted here would go stale, so we link to each vendor’s live pricing page and keep ours on our pricing page.
SlyReply is the product described on this page. Comparisons are made in good faith from publicly available information and may change as these products change. Spotted something out of date? Tell us — we’ll correct it.