Inbox Zero

What it does

According to its docs, Inbox Zero connects to your Gmail or Outlook mailbox and sorts new mail as it arrives, by rules you write in plain English.

Out of the box, mail that needs an answer gets a To Reply label and a draft reply in your Drafts folder. The rest is sorted by category, and marketing and cold email are archived out of the inbox. You tune these default rules during onboarding.

Each rule pairs a condition with one or more actions. The condition can be a description the AI matches against, such as an email asking you to set up a call, or a plain match on From, To or Subject. Actions include labeling, archiving, forwarding, drafting or sending a reply, calling a webhook, and notifying you in Slack, Microsoft Teams or Telegram. By default one rule applies per email; a setting lets several match.

The docs say the assistant learns from your corrections. Its rule History shows what matched each email and why, and a Fix action lets you explain a wrong match so the rule updates.

The Cold Email Blocker catches sales pitches that spam filters miss and lets through anyone who has emailed you before, the docs say. On Plus and up, a digest can gather mail from chosen rules into one daily or weekly summary.

All of this runs in the background of Gmail or Outlook, so you keep your email client. Inbox Zero also has its own free email app. The homepage says the assistant's code is open source, and the docs include a guide to self-hosting it.

Who it fits

Inbox Zero fits people who run their own Gmail, Google Workspace or Outlook mailbox and want it sorted before they open it.

On Inbox Zero's pricing page, Starter is for "individuals, entrepreneurs, and executives" and is listed at $18 a user a month billed annually ($20 monthly) in November 2026. Plus, listed at $28 a user a month billed annually ($35 monthly), adds digests, the Slack integration, app integrations and two email accounts per user.

For a team, Organizations add Owner, Admin and Member roles and rules that admins copy to every member's account. Member analytics stay private until each member allows access. On the hosted service, SSO and SCIM are switched on through sales.

Inbox Zero's case studies include DateNight, which it describes as a two-person team, and Clicks Talent, an influencer marketing agency of 50 employees.

I'd shortlist it if the problem is each person's own inbox and you want drafts waiting beside the labels. Compare the other email triage agents before you buy. If the mail lands in a shared support inbox, the support triage playbook fits better, and a sorting agent for your own categories is often the first custom build I recommend.

Limitations

Inbox Zero's Outlook guide says shared mailboxes that you open through your own account aren't supported. Its workaround is for a Microsoft 365 admin to convert one to a regular user mailbox, which needs a license, and connect it as its own account.

Rules run automatically once they're enabled, the security docs say, and a rule can send replies, forward mail or notify the sender. Chat and the messaging channels ask you to confirm before sending, but rules don't, so the docs advise testing new rules and checking History before you rely on outbound actions.

The docs also warn that AI output can be wrong, and that a rule may match an unexpected message.

On Gmail, the default Cold Email rule emails each cold sender to say their message was filtered. Remove that action if you don't want it. Detection covers new mail only.

Several features sit in Early Access, which the docs describe as not yet on all accounts: Reply Zero's reply tracking, Deep Clean, and the context lookups that draw on tools such as HubSpot, Salesforce and Notion. Deep Clean currently works on Gmail only.

If you self-host, the license in its GitHub repository adds a clause that organizations with five or more business users need an enterprise license from Inbox Zero Inc.

Independent ratings are thin for a product with 12,915 GitHub stars. The Chrome Web Store shows 9 ratings and Product Hunt 14 reviews, the App Store says its rating was recently reset, and G2 and Capterra couldn't be read.