# Master Inbox

> Master Inbox is the reply management platform for outbound teams and
> agencies: one unified inbox for every sequencer, LinkedIn, and inbound
> form, with AI labeling and AI reply agents that range from
> human-in-the-loop to fully autonomous. Unlimited users on every plan.
> EU-hosted in Finland and Germany, GDPR-ready with DPAs on file, SOC 2
> in progress. Start with a free 7-day proof of concept.
>
> Not to be confused with the reply tab built into Smartlead or other
> sequencers: those show one tool's own replies. Master Inbox (masterinbox.com)
> is a standalone product that reads every mailbox across every tool you send from.

Last updated: 2026-09-08. Book a call: https://masterinbox.com/demo

## Product
- [The Better Unibox](https://masterinbox.com/unibox): The unibox that merges Smartlead, Instantly, EmailBison, Reply.io, Lemlist and LinkedIn into one AI-labeled inbox, and catches the replies they miss.
- [AI Labeling](https://masterinbox.com/ai-labeling): Every email and LinkedIn reply labeled by intent as it lands. Thirteen default labels or your own taxonomy, on your OpenAI, Anthropic or OpenRouter key.
- [Workflows](https://masterinbox.com/workflows): Label-triggered workflows inside the inbox: Slack cards with an approve button, HubSpot sync, stop the sequence on a booked meeting, webhooks. No Zapier.
- [API and webhooks](https://masterinbox.com/api): A REST API with 150+ endpoints over replies, prospects, labels, views, workflows and workspaces, plus webhooks for every event. Included on every plan.
- [Client workspaces](https://masterinbox.com/client-workspaces): One workspace per client: its own mailboxes, labels, members and limits, cloned in one click, with client logins scoped to their inbox only.
- [Reply Agents](https://masterinbox.com/reply-agents): AI reply agents that answer every outbound reply, follow up, and book meetings on your real calendar. Human-in-the-loop first, autonomous when ready.
- [LinkedIn Inbox](https://masterinbox.com/linkedin-inbox): One inbox for every LinkedIn account: HeyReach, Expandi, Aimfox and native seats, threaded next to email per prospect, with AI labels and CRM sync.
- [Reply Forms](https://masterinbox.com/reply-forms): Reply Forms capture every inbound lead, answer 24/7 with real calendar availability, and book the meeting automatically. Synced to your CRM on arrival.
- [HubSpot Inbox](https://masterinbox.com/hubspot-inbox): Reply to outbound email and LinkedIn from HubSpot itself. Master Inbox routes each reply through your sending domain so threads and headers stay intact.
- [Reporting](https://masterinbox.com/reporting): See who is sitting on a hot lead. SLA tracking on every reply, reply coverage, missed replies, and team performance by channel and label.
- [Integrations](https://masterinbox.com/integrations): The reply layer for your outbound stack: sending, LinkedIn, CRM, calendars, and more.

## Pricing
- [Pricing](https://masterinbox.com/pricing): Agencies from $599/mo, sales teams from $799/mo, Reply Agent from $499/mo.
- Unlimited users on every plan, priced on workspaces and mailboxes, not seats.

## Compare
- [Compare](https://masterinbox.com/compare): See how Master Inbox compares to Front, Missive, Hiver, Hothawk and Smartlead, and browse every alternatives guide in one place.
- [Smartlead's inbox vs Master Inbox](https://masterinbox.com/vs/smartlead-master-inbox): Smartlead's tab shows its own campaign replies in one workspace. Master Inbox reads every mailbox, catches the forwards and works all clients in one queue.
- [Instantly Unibox vs Master Inbox](https://masterinbox.com/vs/instantly-unibox): Instantly Unibox works at five clients and strains at twenty. Master Inbox reads every mailbox across every Instantly workspace and catches what Unibox misses.
- [Master Inbox vs the DIY reply stack](https://masterinbox.com/vs/diy-reply-stack): Forwarded Gmail, thirty tabs, a Zapier-to-Sheet chain or a homegrown inbox: what breaks in each DIY reply stack, from six months of calls, and what replaces it.
- [Front Alternative](https://masterinbox.com/front-alternative): Front is a support inbox priced per seat. Master Inbox is the Front alternative for outbound: unlimited users, every mailbox, LinkedIn, sequencer-native.
- [Hothawk Alternative](https://masterinbox.com/hothawk-alternative): Hothawk pivoted to a cold email sequencer; reply management is now a feature tab that sees only its own campaigns. Master Inbox is built for the reply.
- [Instantly Alternative](https://masterinbox.com/instantly-alternative): Keep Instantly for sending. Instantly's Unibox only sees its own campaigns. Master Inbox reads every mailbox, every tool, every client, LinkedIn included.
- [Missive Alternative](https://masterinbox.com/missive-alternative): Missive is a team inbox priced per user. Master Inbox is the Missive alternative for outbound: unlimited users, every mailbox, LinkedIn, sequencer-native.
- [Smartlead Alternative](https://masterinbox.com/smartlead-alternative): Keep Smartlead for sending. Smartlead's own Master Inbox only sees one workspace. Master Inbox reads every mailbox, every tool, every client, LinkedIn included.
- [Masterinbox Alternative](https://masterinbox.com/masterinbox-alternative): Looking for a masterinbox or unibox alternative? Master Inbox unifies replies from every sequencer, LinkedIn, and inbound forms with AI labels and unlimited users.

## Company & Trust
- [About](https://masterinbox.com/about): Master Inbox is built by a small team who lived the pain of scattered replies running outbound. Meet the founder and how we work.
- [Customers](https://masterinbox.com/customers): How agencies, sales teams, solo operators and high-ticket teams stopped losing replies with one unified inbox, AI labeling and reply agents.
- [Careers](https://masterinbox.com/careers): Master Inbox hires when we find exceptional people, not on a schedule. See how we work and pitch us if you would make the product better.
- [Press](https://masterinbox.com/press): Press kit for Master Inbox: fast facts, founder bio, brand assets, and a direct contact for media inquiries.
- [Security](https://masterinbox.com/security): How Master Inbox secures customer data: EU hosting, encryption, GDPR compliance, DPAs, and subprocessors.
- [Subprocessors](https://masterinbox.com/subprocessors): The third-party subprocessors Master Inbox engages to process customer data under our Data Processing Addendum.
- [Data Processing Agreement](https://masterinbox.com/legal-dpa): Master Inbox's standard Data Processing Agreement (DPA), available to customers to support GDPR compliance.

## Guides
- [Reply Handling](https://masterinbox.com/reply-handling): Master Inbox handles prospect replies, qualifies leads, and books meetings for your outbound campaigns.
- [LinkedIn Inbound Guide](https://masterinbox.com/linkedin-inbound-guide): A guide to booking meetings from LinkedIn inbound, chapter by chapter.
- [Cold Email Reply Rate Calculator](https://masterinbox.com/cold-email-reply-rate-calculator): Predict reply rates with 94% accuracy using real data from 4+ million emails.

## By situation
- [Missed replies](https://masterinbox.com/missed-replies): The six ways cold email replies go missing (forwards, CC, new addresses, reply-to domains, disconnected mailboxes), what each costs, and how to catch every one.
- [Speed to lead](https://masterinbox.com/speed-to-lead): Interested replies answered in minutes: Needs Reply views, a business-hours SLA, Slack cards with the draft, and agents that book while the lead is warm.
- [Client reporting](https://masterinbox.com/client-reporting): Show clients every reply, response time and meeting without a login: forwarded positives, scheduled reports, scoped client logins and SLA reporting.

## Solutions
- [For Agencies](https://masterinbox.com/for/agencies): Every client in one workspace: replies tagged, routed, and answered under SLA.
- [For Outbound Teams](https://masterinbox.com/for/outbound-teams): Every reply from every sequencer captured, labeled, and worked in one inbox.
- [For RevOps](https://masterinbox.com/for/revops): Replies synced to the CRM automatically, so pipeline reflects every conversation.
- [For Local Businesses](https://masterinbox.com/for/local-businesses): Answer every lead before it cools, across email and LinkedIn.

## Integrations
- [All integrations](https://masterinbox.com/integrations): The full directory of tools Master Inbox connects to.
- [Smartlead](https://masterinbox.com/integrations/smartlead): How Master Inbox works with Smartlead.
- [Instantly](https://masterinbox.com/integrations/instantly): How Master Inbox works with Instantly.
- [EmailBison](https://masterinbox.com/integrations/emailbison): How Master Inbox works with EmailBison.
- [Reply.io](https://masterinbox.com/integrations/reply-io): How Master Inbox works with Reply.io.
- [PlusVibe](https://masterinbox.com/integrations/plusvibe): How Master Inbox works with PlusVibe.
- [Salesforge](https://masterinbox.com/integrations/salesforge): How Master Inbox works with Salesforge.
- [Mixmax](https://masterinbox.com/integrations/mixmax): How Master Inbox works with Mixmax.
- [HeyReach](https://masterinbox.com/integrations/heyreach): How Master Inbox works with HeyReach.
- [Aimfox](https://masterinbox.com/integrations/aimfox): How Master Inbox works with Aimfox.
- [Expandi](https://masterinbox.com/integrations/expandi): How Master Inbox works with Expandi.
- [SalesFlow](https://masterinbox.com/integrations/salesflow): How Master Inbox works with SalesFlow.
- [SalesRobot](https://masterinbox.com/integrations/salesrobot): How Master Inbox works with SalesRobot.
- [Lemlist](https://masterinbox.com/integrations/lemlist): How Master Inbox works with Lemlist.
- [Valley](https://masterinbox.com/integrations/valley): How Master Inbox works with Valley.
- [HubSpot](https://masterinbox.com/integrations/hubspot): How Master Inbox works with HubSpot.
- [Pipedrive](https://masterinbox.com/integrations/pipedrive): How Master Inbox works with Pipedrive.
- [Attio](https://masterinbox.com/integrations/attio): How Master Inbox works with Attio.
- [GoHighLevel](https://masterinbox.com/integrations/gohighlevel): How Master Inbox works with GoHighLevel.
- [Salesforce](https://masterinbox.com/integrations/salesforce): How Master Inbox works with Salesforce.
- [Cal.com](https://masterinbox.com/integrations/cal-com): How Master Inbox works with Cal.com.
- [Calendly](https://masterinbox.com/integrations/calendly): How Master Inbox works with Calendly.
- [TidyCal](https://masterinbox.com/integrations/tidycal): How Master Inbox works with TidyCal.
- [Chili Piper](https://masterinbox.com/integrations/chili-piper): How Master Inbox works with Chili Piper.
- [Findymail](https://masterinbox.com/integrations/findymail): How Master Inbox works with Findymail.
- [Icypeas](https://masterinbox.com/integrations/icypeas): How Master Inbox works with Icypeas.
- [Prospeo](https://masterinbox.com/integrations/prospeo): How Master Inbox works with Prospeo.
- [BetterContact](https://masterinbox.com/integrations/bettercontact): How Master Inbox works with BetterContact.
- [Clay](https://masterinbox.com/integrations/clay): How Master Inbox works with Clay.
- [Apollo](https://masterinbox.com/integrations/apollo): How Master Inbox works with Apollo.
- [RB2B](https://masterinbox.com/integrations/rb2b): How Master Inbox works with RB2B.
- [Slack](https://masterinbox.com/integrations/slack): How Master Inbox works with Slack.
- [Google Sheets](https://masterinbox.com/integrations/google-sheets): How Master Inbox works with Google Sheets.
- [Zapier](https://masterinbox.com/integrations/zapier): How Master Inbox works with Zapier.
- [n8n](https://masterinbox.com/integrations/n8n): How Master Inbox works with n8n.
- [Notion](https://masterinbox.com/integrations/notion): How Master Inbox works with Notion.
- [OpenAI](https://masterinbox.com/integrations/openai): How Master Inbox works with OpenAI.
- [Ashby](https://masterinbox.com/integrations/ashby): How Master Inbox works with Ashby.
- [Google Calendar](https://masterinbox.com/integrations/google-calendar): How Master Inbox works with Google Calendar.
- [SmartMoving](https://masterinbox.com/integrations/smartmoving): How Master Inbox works with SmartMoving.
- [Close](https://masterinbox.com/integrations/close): How Master Inbox works with Close.
- [LeadMagic](https://masterinbox.com/integrations/leadmagic): How Master Inbox works with LeadMagic.
- [SIGNALIZ](https://masterinbox.com/integrations/signaliz): How Master Inbox works with SIGNALIZ.
- [Signalbase](https://masterinbox.com/integrations/signalbase): How Master Inbox works with Signalbase.

## Glossary
- [Outbound Reply Management Glossary](https://masterinbox.com/glossary): 41 plain-language definitions of outbound terms.
- [Unibox](https://masterinbox.com/glossary/unibox): A unibox is a single inbox view that pulls incoming replies from every mailbox and sending domain in a cold email campaign into one place, so a sender never has to check dozens of separate inboxes to find who wrote back.
- [Master Inbox](https://masterinbox.com/glossary/master-inbox): A master inbox is a centralized workspace where every reply from every outbound channel and mailbox is collected, classified, and routed to the right person, functioning as the single source of truth for outbound conversations.
- [Unified Inbox](https://masterinbox.com/glossary/unified-inbox): A unified inbox is any tool that merges messages from multiple accounts, channels, or platforms into a single feed, letting a user read and respond without switching between separate apps.
- [Reply Management](https://masterinbox.com/glossary/reply-management): Reply management is the set of processes and tools used to capture, classify, prioritize, and respond to inbound replies generated by outbound campaigns, from the moment a prospect writes back to the moment a meeting is booked or the lead is disqualified.
- [Positive Reply Rate](https://masterinbox.com/glossary/positive-reply-rate): Positive reply rate is the percentage of sent emails that generate a genuinely interested response, such as a request for more information or a meeting, calculated by dividing positive replies by total emails sent.
- [Reply Rate](https://masterinbox.com/glossary/reply-rate): Reply rate is the percentage of sent emails that receive any response at all, positive, negative, or neutral, calculated by dividing total replies by total emails delivered.
- [Response SLA](https://masterinbox.com/glossary/response-sla): A response SLA, or service level agreement, is the maximum time a team commits to responding to an inbound reply, often set at minutes for hot leads and hours for standard ones.
- [Inbox Rotation](https://masterinbox.com/glossary/inbox-rotation): Inbox rotation is the practice of distributing outbound sends across many mailboxes and sending domains rather than one, cycling through them so no single inbox sends a volume that triggers spam filters.
- [Email Warmup](https://masterinbox.com/glossary/email-warmup): Email warmup is the process of gradually increasing send volume and engagement on a new mailbox, often using automated warmup networks that exchange emails and mark them as good, to build sender reputation before the mailbox is used for cold outreach.
- [Sending Domain](https://masterinbox.com/glossary/sending-domain): A sending domain is the domain name used to send cold outbound email, distinct from a company's primary website domain, chosen specifically to protect the main domain's reputation if something goes wrong with deliverability.
- [Secondary Domain](https://masterinbox.com/glossary/secondary-domain): A secondary domain is an additional domain, often a close variant of a company's primary domain name, registered specifically for sending cold outbound email at scale.
- [Out-of-Office Handling](https://masterinbox.com/glossary/out-of-office-handling): Out-of-office handling is the automated detection and filtering of auto-reply messages, such as vacation responders, so they do not clutter a reply queue or get miscounted as genuine engagement.
- [Bounce](https://masterinbox.com/glossary/bounce): A bounce is a delivery failure notification sent back to the sender when an email cannot be delivered to the recipient's inbox, generated by the receiving mail server rather than the recipient.
- [Soft Bounce](https://masterinbox.com/glossary/soft-bounce): A soft bounce is a temporary delivery failure, typically caused by a full inbox, an oversized message, or a server that is briefly unavailable, where the receiving server may accept the email if it is sent again later.
- [Hard Bounce](https://masterinbox.com/glossary/hard-bounce): A hard bounce is a permanent delivery failure, caused by an invalid, nonexistent, or blocked email address, where the receiving server rejects the message outright and will keep rejecting it on future attempts.
- [Deliverability](https://masterinbox.com/glossary/deliverability): Deliverability is the measure of how successfully an email reaches a recipient's primary inbox rather than being filtered to spam or blocked entirely, shaped by sender reputation, authentication records, content quality, and recipient engagement.
- [Spam Complaint Rate](https://masterinbox.com/glossary/spam-complaint-rate): Spam complaint rate is the percentage of delivered emails that a recipient marks as spam or junk, calculated by dividing complaints by emails delivered.
- [Sequencer](https://masterinbox.com/glossary/sequencer): A sequencer is the software used to schedule and send a series of outbound emails, and often other channel touches, to a list of prospects according to a defined sequence and cadence.
- [Sequence](https://masterinbox.com/glossary/sequence): A sequence is a predefined series of outbound touches, such as an initial email followed by scheduled follow-ups, sent to a prospect over a set period of time according to a fixed cadence.
- [Follow-Up Cadence](https://masterinbox.com/glossary/follow-up-cadence): Follow-up cadence is the timing and spacing of touches within a sequence, such as an initial email followed by reminders three, seven, and fourteen days later.
- [Intent Classification](https://masterinbox.com/glossary/intent-classification): Intent classification is the process of categorizing an inbound reply by what the sender actually means, such as interested, not interested, referral, out of office, or unsubscribe, so the reply can be routed and prioritized correctly.
- [Reply Labeling](https://masterinbox.com/glossary/reply-labeling): Reply labeling is the act of tagging an inbound message with a category, such as interested, meeting request, wrong person, or unsubscribe, so it can be filtered, searched, and reported on later.
- [Lead Routing](https://masterinbox.com/glossary/lead-routing): Lead routing is the automated process of sending a qualified or interested lead to the right person, team, or CRM record based on rules such as territory, deal size, or which rep owns the original outbound send.
- [Meeting Booked Rate](https://masterinbox.com/glossary/meeting-booked-rate): Meeting booked rate is the percentage of positive replies, or alternatively of total emails sent, that convert into a scheduled meeting on a rep's calendar.
- [Show Rate](https://masterinbox.com/glossary/show-rate): Show rate is the percentage of booked meetings where the prospect actually attends, calculated by dividing meetings held by meetings booked.
- [Cold Email](https://masterinbox.com/glossary/cold-email): Cold email is unsolicited outbound email sent to a recipient with whom the sender has no prior relationship, typically used to introduce a product, service, or opportunity.
- [Cold Outbound](https://masterinbox.com/glossary/cold-outbound): Cold outbound is the broader category of unsolicited prospecting across any channel, including cold email, cold calling, and LinkedIn outreach, aimed at starting a conversation with someone who has not previously engaged with the company.
- [Multichannel Outreach](https://masterinbox.com/glossary/multichannel-outreach): Multichannel outreach is a prospecting approach that combines two or more channels, most commonly email and LinkedIn, within a single coordinated sequence to reach a prospect through more than one touchpoint.
- [LinkedIn Outreach](https://masterinbox.com/glossary/linkedin-outreach): LinkedIn outreach is prospecting conducted through LinkedIn's messaging features, including connection requests, InMail, and direct messages to existing connections, used as a standalone channel or alongside cold email in a multichannel sequence.
- [Connection Request](https://masterinbox.com/glossary/connection-request): A connection request is an invitation sent through LinkedIn asking another user to join their professional network, optionally including a short personalized note.
- [InMail](https://masterinbox.com/glossary/inmail): InMail is a paid LinkedIn messaging feature that lets a sender message another LinkedIn user directly without first sending a connection request or being connected.
- [Social Selling](https://masterinbox.com/glossary/social-selling): Social selling is the practice of using social platforms, primarily LinkedIn in a B2B context, to build relationships with prospects through content, engagement, and direct outreach rather than relying solely on cold email or cold calls.
- [CRM Sync](https://masterinbox.com/glossary/crm-sync): CRM sync is the automated, bidirectional flow of data between an outbound or reply management tool and a customer relationship management system, such as Salesforce or HubSpot, keeping contact records, activity history, and deal stages up to date in both places.
- [Shared Inbox](https://masterinbox.com/glossary/shared-inbox): A shared inbox is an email inbox accessible to multiple team members at once, letting several people view, assign, and respond to the same stream of messages, commonly used for addresses like support@ or sales@.
- [Help Desk vs. Shared Inbox](https://masterinbox.com/glossary/help-desk-vs-shared-inbox): Help desk versus shared inbox describes the choice between two categories of collaborative email tools: a help desk adds ticketing structure, such as status, SLAs, and queues, on top of email, while a shared inbox offers simpler collaborative access without formal ticket workflows.
- [SDR (Sales Development Representative)](https://masterinbox.com/glossary/sdr): An SDR, or sales development representative, is a sales role focused on prospecting and qualifying inbound and outbound leads, typically handing off qualified opportunities to an account executive rather than closing deals themselves.
- [BDR (Business Development Representative)](https://masterinbox.com/glossary/bdr): A BDR, or business development representative, is a sales role similar to an SDR, focused on outbound prospecting to generate qualified pipeline, though some companies use the title to distinguish outbound-focused reps from SDRs who handle inbound leads.
- [RevOps (Revenue Operations)](https://masterinbox.com/glossary/revops): RevOps, or revenue operations, is the function responsible for aligning the systems, data, and processes across sales, marketing, and customer success so that revenue-generating teams operate on consistent tools and reporting.
- [Lead-Gen Agency](https://masterinbox.com/glossary/lead-gen-agency): A lead-gen agency is a third-party service provider that runs outbound prospecting campaigns, typically cold email and LinkedIn outreach, on behalf of client companies, delivering qualified leads or booked meetings as the core service.
- [White Label](https://masterinbox.com/glossary/white-label): White label describes a product or service that a company rebrands and resells under its own name, hiding the original provider, commonly used by agencies that want client-facing tools and reports to appear as their own.
- [Proof of Concept (POC)](https://masterinbox.com/glossary/proof-of-concept-poc): A proof of concept, or POC, is a limited, time-boxed trial of a tool or process with a real but small dataset, used to confirm it works as expected before a full commitment or rollout.

## Blog
- [7 Best Front Alternatives: Features, Pricing, Pros & Cons](https://masterinbox.com/blog/7-best-front-alternatives)
- [Master Inbox vs Front: Which one should you choose?](https://masterinbox.com/blog/master-inbox-vs-front)
- [Master Inbox vs Hiver: Which one should you choose?](https://masterinbox.com/blog/master-inbox-vs-hiver)
- [Master Inbox vs Smartlead: Which one should you choose?](https://masterinbox.com/blog/masterinbox-vs-smartlead)