CampaignStack
Product · Email Sending

Send from your own Gmail.
Without burning it.

Connect Google once and your workflows can send email. Every inbox gets a daily budget that grows as you send and shrinks when you stop. New inboxes warm up before campaigns touch them.

01 · Connect Google

One OAuth flow, everything connected.

One authorization covers sending, calendar, and contacts. No per-service setup, no config screens. Click the button, pick the account, done.

One click
Connect Google
One OAuth screen, one consent
Gmail sending
Campaign email goes out from your own address, not a shared relay.
Calendar
Availability checks, free slots, and event creation for booking meetings.
Contacts
Match inbound replies to people you already know.
Connect once per inbox. Every workflow in the workspace can send through it, and every send is counted against that inbox's daily budget.
02 · Email in workflows

A node in the flow,
not a separate tool.

Drop an email step anywhere in a workflow. The AI writes each message from the lead's context and your brand voice. Add a review gate and nothing sends until you approve it.

Email step inside a workflowCraft → review → send
01
Craft
AI writes the email from lead context, campaign goal, and your brand voice.
02
Review
Optional gate. Approve, edit inline, or reject before anything is sent.
HUMAN STEP
03
Send
Delivered through your Gmail, deducted from the account's daily budget.
Review-first is the default. Autopilot is a per-campaign choice, not a commitment. Flip it whenever you trust the drafts.
03 · Daily send budget

Limits that earn their own headroom.

Every connected inbox gets a daily cap based on its age and history. Consistent sending grows it, going quiet shrinks it. Same protection philosophy as our LinkedIn safety system.

Today · lucas@agency.io
34 / 80 emails sent
Capacity
40%
Active day+4pp

Send at least one email and tomorrow's capacity grows.

One idle dayGrace

A single day off costs nothing. A weekend won't set you back.

Idle streak×0.82

Stay quiet and capacity decays back toward the 10% floor.

New accounts start at 10% of their base limit. Full capacity takes about 23 active sending days. When the budget is spent, sends wait for the next day instead of failing.
04 · Mailbox warmup

Reputation first, campaigns second.

A brand-new inbox that starts blasting cold email lands in spam. Warmup builds a sender reputation with real email traffic first, then gets out of the way.

Automated warmup

WARMING
Sender reputation score62 / 100
At a score of 80, warmup suspends itself. The inbox is ready and stops accruing cost.

Your inbox exchanges real emails with a network of live inboxes, replies included, until providers treat it as a normal sender. One-time credit cost per inbox, no subscription.

Already warmed?

An inbox that's been sending for years doesn't need the treatment. Mark it as warmed and skip straight to campaigns.

Mark as warmed · free
05 · Calendar

Reply, propose a slot, book the meeting.

The point of outreach is a meeting on the calendar. With Calendar connected, CampaignStack checks availability, finds free slots, and creates the event without leaving the conversation.

From reply to booked meeting
Free slots found
Tuesday10:00
Tuesday14:30Picked
Wednesday09:00
Event created
Intro call · Sarah Patel
Tuesday 14:30 · 30 min
Invite sent to both sides, straight from the conversation.
06 · MCP · API-first

Every email feature is an MCP tool.

Send email, check budgets, run warmup, and book meetings from any AI agent or script. If the UI can do it, the API can do it.

Send and book from any agentAgent-ready
// An AI agent can run the whole email motion
await agent.callTool("campaignstack_send_gmail", {
to: "sarah@retailflow.io",
subject: "Quick question about RetailFlow",
});
await agent.callTool("campaignstack_get_free_slots", {
durationMinutes: 30,
});
Sending, warmup, and calendar tools ship on the same MCP server as everything else. Budgets apply no matter who calls.

Connect Google. Start sending.

Your first inbox connects in under a minute. The safety system takes it from there.

Start free trial