Master Inbox
One AI-labeled inbox for every email and LinkedIn reply from Smartlead, Instantly, EmailBison and HeyReach, with client workspaces.
From $599/mo API
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Bottom line
Master Inbox collects every cold email and LinkedIn reply from your sequencers into one AI-labeled inbox, with a separate workspace for each client. It suits outbound agencies and recruiting firms running business development across many mailboxes and clients. Plans start at $599 a month on annual terms billed monthly, and the vendor runs a free 7-day proof of concept on your own inboxes.
Stands out for: It reads the mailboxes themselves rather than relying on the sequencer's reply feed, so forwards, CC replies and replies from new addresses show up alongside the rest, which a sequencer unibox such as Instantly's can miss. Unlimited users on every plan and per-client workspaces with scoped client logins make it built for agencies that hand reply handling to a team.
Watch out for: The entry price of $599 a month is high for a solo recruiter or a small desk, and month to month billing adds 25%. Native Salesforce sync is not available yet and runs through webhooks or the OutboundSync partnership, and AI usage is paid separately on your own model key.
Overview
Master Inbox is a reply management platform for teams that send cold outbound at volume. It connects to sequencers such as Smartlead, Instantly, EmailBison, Reply.io, PlusVibe and Salesforge, and to LinkedIn tools such as HeyReach, Expandi, Aimfox and Lemlist, then puts every reply in one filterable inbox.
Each reply is labeled by intent as it lands, using thirteen default labels or your own, and the model runs on your own OpenAI, Anthropic or OpenRouter key. Reply agents can draft responses, follow up and book meetings on Cal.com, Calendly, Chili Piper or Google Calendar, with human approval as the default.
Agencies get a workspace per client with its own mailboxes, labels, members and limits, plus client reporting that can be shared without a login. Workflows triggered by labels can post a Slack card with an approve button, sync to HubSpot, stop a sequence when a meeting books and fire webhooks.
Pricing follows mailboxes and client workspaces rather than seats. Data is hosted in the EU, in Finland and Germany, and a REST API with more than 150 endpoints is included on every plan.
Who it's for
Best for
- Outbound agencies managing replies for many clients
- Teams running several sequencers and LinkedIn tools at once
- Agencies that want to give clients a scoped inbox login
- RevOps leads tracking missed replies and response time
Not ideal for
- Solo recruiters with a handful of mailboxes
- Teams that need native Salesforce sync
- Buyers who want a low monthly entry price
Key features
One inbox for every sequencer. Replies from Smartlead, Instantly, EmailBison, Reply.io, PlusVibe and others land in one queue, including forwards and replies from new addresses that a sequencer misses.
LinkedIn threaded with email. HeyReach, Expandi, Aimfox and native LinkedIn seats feed the same inbox, threaded per prospect next to the email conversation.
AI labeling on your own key. Every reply is labeled by intent using your own OpenAI, Anthropic or OpenRouter key, with no markup on model usage.
AI reply agents. Agents draft answers and book meetings on Cal.com, Calendly or Google Calendar, starting with a human approving each draft.
Client workspaces. Each client gets its own mailboxes, labels and members, workspaces clone in one click, and client logins see only their own inbox.
Workflows and API. Label-triggered workflows post Slack cards, sync to HubSpot and stop sequences, and a REST API with 150+ endpoints plus webhooks is included on every plan.
AI features
| What the AI does | Plan |
|---|---|
Only features named in the vendor's own documentation. Anything sold separately is marked as an add-on.
Pricing
| Plan | Price | What you get |
|---|---|---|
| Agency | $599/mo | 15 client workspaces, 3,000 mailboxes |
| Scale | $1,297/mo | 40 client workspaces, 15,000 mailboxes, SSO, provisioning API |
| Unlimited | $1,697/mo | Unlimited client workspaces, 30,000 mailboxes |
| Team | $799/mo | 2,000 mailboxes, unlimited seats |
| Revenue | $1,499/mo | 7,500 mailboxes, HubSpot Suite, round-robin |
| Enterprise | From $2,500/mo | Annual; SSO, EU data residency, named CSM |
Master Inbox prices on client workspaces and mailboxes, with unlimited users on every plan. Listed prices are annual, billed monthly; month to month costs 25% more and annual prepaid saves 15%. For agencies, Agency is $599 a month for 15 client workspaces and 3,000 mailboxes, Scale is $1,297 a month for 40 workspaces and 15,000 mailboxes, and Unlimited is $1,697 a month for unlimited workspaces and 30,000 mailboxes. A Ramp option for agencies with fewer than five clients starts at $299 a month with a $500 onboarding fee that is credited back. For in-house teams, Team is $799 a month for 2,000 mailboxes and Revenue is $1,499 a month for 7,500 mailboxes. Enterprise and the white-label Platform plan start at $2,500 a month on annual terms. The vendor offers a free 7-day proof of concept on your own inboxes. Confirm current terms on the vendor site.
Checked 4 Nov 2026. Vendors change prices without notice.
Is Master Inbox expensive?
Master Inbox does not publish a price. It is one of 22 quote-based tools among the 144 outreach tools in our directory. 30 have a free tier, and those with a public price typically start around $49 a month.
- 22 quote-based
- 30 free tier
- 122 public price
Worked out automatically from every outreach listing, so it updates as the directory changes.
Pros and cons
Pros
- Unlimited users on every plan
- Catches forwards and replies sequencers miss
- Per-client workspaces with scoped logins
Cons
- Starts at $599 a month
- Salesforce not native yet
- AI usage billed on your own model key
Integrations
Smartlead Instantly EmailBison HeyReach HubSpot Slack Calendly Cal.com
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How Master Inbox compares
See all Master Inbox alternatives, with what each one does differently and a head to head for every pairing.
| Tool | Free tier | From | MCP | API | Compare |
|---|---|---|---|---|---|
| | – | $599/mo | – | ✓ | |
| | – | $37.60/mo | ✓ | ✓ | Compare |
| | – | $99/mo | – | ✓ | Compare |
 Breakcold Breakcold is a cheaper sales CRM with a social and email inbox for small teams, while Master Inbox is priced and built for agencies at volume. | – | $59/mo | ✓ | ✓ | Compare |
$37.60/mo MCP API
Instantly's built-in unibox covers replies for Instantly campaigns only, while Master Inbox merges several sequencers and LinkedIn tools.
$99/mo API
OutboundSync pushes sequencer replies into your CRM rather than giving you an inbox to work them, and Master Inbox integrates with it.
Breakcold$59/mo MCP API
Breakcold is a cheaper sales CRM with a social and email inbox for small teams, while Master Inbox is priced and built for agencies at volume.
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