Build outbound with Claude, down to the mailboxes

Point Claude, ChatGPT or Cursor at your sending.ac account through the MCP server, or call the API directly. Domains, mailboxes, DNS and warm-up become things your agent can create.

Read the docs Talk to an advisor

213K mailboxes under management
Works with

Claude + sending.ac MCP

# Prompt in Claude, with the sending.ac MCP server connected
> create 4 domains, 3 mailboxes each, start warm-up today

# The calls behind it
POST /v1/domains
{ "count": 4, "tld": ".co" }

POST /v1/mailboxes
{ "domains": 4, "per_domain": 3, "provider": "azure", "warm_up": true }

Agents write the copy, then stall at infrastructure

Infrastructure lives behind dashboards

An agent can research leads and draft sequences. Then a person clicks through a registrar, DNS settings and a mailbox provider to give it something to send from.

Hand-typed DNS breaks the pipeline

SPF, DKIM and DMARC entered by hand, per domain. One wrong record and that domain sends unauthenticated, and nothing downstream in the agent notices.

The agent can't see placement

A pipeline that only reads send counts keeps sending through a domain whose placement is slipping.

One slipping domain, two different pipelines

An example week

An agent reading send counts

Monday
Placement slips on try-outreach.co. Send counts still look normal.
Tuesday
The agent keeps queueing sequences through the same domain.
Thursday
Replies dry up and nobody can say which domain.
Next week
Someone traces it by hand and types DNS for new domains.

Monday
The placement check flags try-outreach.co.
Monday
The failure comes with what broke, why and what to do, readable over the API.
Monday
The agent provisions a replacement domain, with DNS verified before the first send.
Thursday
Replies hold and nobody had to step in.

What your agent can do on sending.ac

Provision from a prompt

The MCP server exposes your account to Claude, ChatGPT or Cursor. Ask for four domains with three mailboxes each and warm-up starting today, and the agent creates them, with DNS written and verified per domain.

Mailboxes on Azure or Google
Any TLD
Up to 75 mailboxes per domain on Azure

sending.acDefault workspace

SequencersDomainsPersonasInboxesDeliverability

DomainsCreated just now

create 4 domains, 3 mailboxes each, start warm-up todayvia MCP

Domain	DNS	Warm-up
get-outreach.co3 inboxes · Azure	Verified	WarmingStarted today
try-outreach.co3 inboxes · Azure	Verified	WarmingStarted today
outreach-hq.co3 inboxes · Azure	Verified	WarmingStarted today
go-outreach.co3 inboxes · Azure	Verified	WarmingStarted today

A route for AI-SDR products

If you are building an AI-SDR product, the full API lets your product provision mailboxes for its own users, with a wholesale route for volume. Each domain still runs on its own tenant with monitoring on every domain.

Full API and an MCP server
Mailboxes connect to Instantly, Smartlead, EmailBison, PlusVibe
Wholesale terms through an advisor

Your product on sending.ac

Your AI-SDR productWrites and sends the outreach

sending.ac APIDomains, mailboxes, DNS, warm-up

A tenant per domainOwn IPs, own reputation

Monitoring7 checks per domain, every day

Works where you already build

Connect the MCP server to the assistant you use, or call the API from your own product. Both reach the same account, the same domains and the same daily checks.

MCP server for Claude, ChatGPT and Cursor
Full API for your own product
Mailboxes connect to Instantly, Smartlead, EmailBison, PlusVibe

One account · MCP and API

ClaudeMCP

ChatGPTMCP

CursorMCP

Your productAPI

Teams running outbound on sending.ac

213Kmailboxes under management

7checks per domain, every day

30 daysto replace a burned mailbox

75mailboxes on a single domain

Sergio PereaInbox buyer

Message

Btw, you guys have the smoothest UX/UI of all the inbox resellers I’ve purchased from. And I’ve worked with ALL of them.

From connected agent to first send

Connect the MCP server or the API
Point Claude, ChatGPT or Cursor at your account, or call the API from your own code.
Ask for domains and mailboxes
The agent creates them, and DNS is written and verified per domain before the first send.
Send from your sequencer
The mailboxes connect to Instantly, Smartlead, EmailBison or PlusVibe. Warm-up takes its usual few weeks.

Questions builders ask

Most of these are faster on a 15-minute call with someone who already knows the answer.

Talk to an advisor

Which assistants work with the MCP server?

Claude, ChatGPT and Cursor. Everything the MCP server does is also in the full API.

Can my product provision mailboxes for its own users?

Yes. The API lets your product provision for its customers, with a workspace per customer, walled off from the others. Ask an advisor about wholesale terms for volume.

Does the agent have to write DNS records?

No. SPF, DKIM and DMARC are written and verified per domain before the first send.

Can the agent see when a domain is in trouble?

Yes. The same seven daily checks we run on every domain are readable over the API, so a pipeline can act on a failing domain instead of sending through it.

What happens when a mailbox burns?

Risk Level flags it from sending data before the reply rate shows it. Mailbox insurance replaces it within 30 days at no extra cost, even if it was bought elsewhere. Insurance is free and in early access.

Which sequencers do the mailboxes work with?

Instantly, Smartlead, EmailBison and PlusVibe connect natively.

Point your agent at a real account

Read the API and MCP reference, or talk through the wholesale route with a deliverability advisor.