Unlimited Multi-Mailbox Cold Email Sending

Why Do Seat-Based Sequencers Break at Scale?

Most cold email sequencers charge per mailbox seat, which forces outbound teams into a painful tradeoff: either pay escalating platform fees as mailbox count grows, or cram more volume through fewer mailboxes and burn them faster. Agencies running 200+ client mailboxes can easily pay five figures per month in seat fees before sending a single email.

Superkabe removes the seat constraint entirely. Connect as many Google Workspace accounts, Microsoft 365 accounts, or custom SMTP mailboxes as your infrastructure supports. The platform scales with your sending fleet, not against it — because the real cost of outbound is domain reputation, not platform seats.

What Providers Does Superkabe Support?

Superkabe supports three mailbox classes natively. Google Workspace accounts connect via OAuth, with full API-level send and reply tracking. Microsoft 365 accounts connect via MSAL-based OAuth against the Microsoft Graph API, with the same telemetry fidelity. Custom SMTP providers — including Zapmail, Scaledmail, MissionInbox, and any IMAP/SMTP-compatible infrastructure — connect via credentialed connection profiles with send-throttling, DKIM validation, and bounce capture built in.

All three classes feed into the same unified sending pipeline. A single campaign can mix Google, Microsoft, and custom SMTP senders in one rotation, and the routing engine chooses the best available mailbox for each lead regardless of provider class.

How Does Per-Mailbox Governance Prevent Fleet-Wide Damage?

When you connect 100 mailboxes to a traditional sequencer, you are effectively operating 100 independent risk surfaces with no coordinated defense. One bad lead list sent through five mailboxes can simultaneously degrade five domain reputations before anyone logs in to check dashboards.

Superkabe enforces mailbox-level governance from the first send. Every mailbox carries independent send limits, warmup state, health score, and pause authority. When one mailbox begins drifting — bounce rate rising, deferral rate spiking, reply rate collapsing — the platform pauses that specific mailbox and redistributes its queued volume across the healthy remainder. The rest of the fleet continues sending uninterrupted, and no single bad send can cascade across your infrastructure.

This per-mailbox isolation is what makes unlimited scaling safe. Adding your 200th mailbox does not add 200th-mailbox risk; it adds 200th-mailbox capacity, because the governance layer contains damage at the individual sender level.

How Is Provisioning Handled for New Mailboxes?

Connecting a new mailbox is a single OAuth flow (Google / Microsoft) or a single credential form (custom SMTP). Superkabe automatically registers the mailbox in the protection layer, initializes its warmup profile, sets starting volume limits based on domain age and prior reputation signals, and enrolls it in the bounce-monitoring pipeline.

From the moment a mailbox is connected, it is governed. There is no separate "add to monitoring" step and no risk of an orphaned sender operating outside the protection layer.