APP IDEA #4 · B2B · EMAIL INFRASTRUCTURE

ColdSire — cold email infrastructure as a service for 600+ agencies

ColdSire handles the infrastructure layer that kills most cold email campaigns before they start — bulk domain registration, automated SPF/DKIM/DMARC setup, mailbox creation, and deliverability monitoring. Trusted by 600+ agencies. The one-time payment model (no subscription lock-in) is the pricing differentiator.

600+

Agencies and sales teams using it

One-time

Payment model — no monthly lock-in vs competitors

Auto

SPF, DKIM, DMARC configured automatically on every domain

24hr

Claimed support response time

01 / HOW IT WORKS

What the app actually does

Cold email works — when it lands in the inbox. ColdSire's entire product is solving the infrastructure problem that causes most campaigns to land in spam before a human has even seen them.

Agency or sales team provides a list of domains to register

New domains unrelated to the main brand — "sending domains" that protect deliverability of the primary domain.

ColdSire registers domains and creates mailboxes in bulk automatically

No manual DNS setup per domain — the platform handles SPF, DKIM, and DMARC configuration automatically across all domains.

Ongoing monitoring tracks sender reputation and deliverability health

Dashboard shows bounce rates, spam flags, and authentication status — problems are caught before they tank entire campaigns.

Seamlessly integrates with Instantly.ai and SmartLead

The cold email sending tools connect to the ColdSire-managed inboxes — infrastructure and sending tool work together without manual bridging.

02 / INDIA POTENTIAL

Does this work as an India play

India's B2B sales and digital agency ecosystem is growing fast and cold email is the dominant outbound channel. Most agencies are still manually configuring DNS records or paying premium prices to global providers.

Agencies

15,000+ Indian digital marketing and B2B sales agencies rely on cold email as a core service — a built-in distribution channel.

Rupee

An India-priced infrastructure tool (₹3,999/month vs global tools pricing in dollars) opens the mid-market agency segment.

Warmup

Email warmup services bundled with infrastructure — combining the two is a gap in the Indian market specifically.

Cold WhatsApp outreach infrastructure (separate sending numbers, verified business accounts) as a second product for the Indian market where WhatsApp outreach is heavy.

03 / THE WEEKEND BUILD

Friday to Sunday, hour by hour

More backend-heavy than most guides, but a working MVP is still achievable. The main non-code prerequisites (registrar reseller account, mail provider API) need to be set up before writing any code.

Friday

Evening · 3 hrs

7–8 PM Set up a Next.js project, Supabase, and connect to a domain registrar API (Namecheap, GoDaddy, or Cloudflare).

8–9 PM Build the domain registration form and the API call that programmatically registers a list of provided domains.

9–10 PM Build the automated DNS record creation — POST the SPF, DKIM, and DMARC records via the registrar DNS API after each registration.

Saturday

Full day · 7 hrs

Morning Build the mailbox creation flow — connect to Google Workspace Admin API or Zoho Mail API to create mailboxes on each registered domain.

Afternoon Build the deliverability monitoring dashboard — check each domain authentication status and flag anything not properly configured.

Evening Build the integration export for Instantly.ai/SmartLead — output the mailboxes in the format each tool expects for import.

Sunday

5 hrs

Morning Add email warmup scheduling — a basic daily sending/receiving loop that builds sender reputation on new mailboxes.

Afternoon Razorpay integration — Rs3,999/month for up to 20 domains, higher tiers for volume.

Evening Test end-to-end with a real domain registration, confirm DNS records are correct, record the demo for your first post.

04 / APP STACK

What you're actually building with

Next.js 14

Frontend + API routes

Domain management dashboard and the backend calls to registrar/mail provider APIs.

Supabase

Auth + database

Stores domain registrations, mailbox assignments, and deliverability monitoring data.

Dns

Registrar API (Namecheap/Cloudflare)

Domain + DNS management

Programmatically registers domains and sets DNS records — the core automation.

Gws

Google Workspace or Zoho API

Mailbox creation

Creates mailboxes on each domain automatically after DNS setup.

Razorpay

Payments

Rs3,999/month subscription based on number of managed domains.

Tailwind CSS

Styling

Fast enough to build the domain management dashboard in a weekend.

05 / WHERE & HOW TO DEPLOY

Going live

Where: Vercel for the app, Supabase for the database. The domain registrar reseller API access and Google Workspace reseller account are non-code prerequisites that must be set up before building.

Set up a registrar reseller account (Namecheap reseller or Cloudflare) BEFORE writing any code — this gives API access for bulk domain registration.

Set up Google Workspace reseller access or a Zoho Mail account for programmatic mailbox creation.

Push your project to GitHub, import into Vercel, add environment variables.

Deploy and test the full domain registration to DNS to mailbox flow on a real domain before going live.

Point a custom domain at it from Vercel domain settings.

06 / MARKETING & REVENUE

Getting paying users

How to market it

Post the "set up 20 cold email sending domains in 5 minutes, fully authenticated" demo as a reel.
Run 10-20 reels/day across multiple accounts targeting agency owners, sales managers, and outbound consultants separately.
Get listed in Indian agency and sales communities — most easily discovered by people already running cold email campaigns.
Offer a free first-domain setup so agencies can verify the automation works before committing to a monthly plan.
A one-time payment model (like ColdSire itself) is a strong differentiator vs monthly competitors — consider this pricing approach.

Who pays, and why

Indian digital marketing and B2B sales agencies running cold email campaigns for clients.
SaaS founders doing their own outbound sales who understand cold email but do not want to manually configure infrastructure.
Outsourced SDR teams and appointment-setting agencies scaling outreach campaigns.

Scenario

Paying users/mo

Revenue/mo

Slow start

30 agencies x Rs3,999

Rs1,19,970

Agency community traction + reels

300 agencies x Rs3,999

Rs11,99,700

10-20 reels/day + agency partnerships

1,000 agencies x Rs3,999

Rs39,99,000

07 / START BUILDING

Paste this into Claude or GPT

This prompt sets up the full build context so the AI scopes, plans, and starts coding the project with you from message one.

BUILD_PROMPT.txt

I want to build a cold email infrastructure automation tool for the Indian market, inspired by ColdSire, scoped to ship a working version in a single weekend. Core flow: 1. Agency provides a list of domains to register for cold outreach. 2. Platform programmatically registers each domain via a registrar API. 3. SPF, DKIM, and DMARC DNS records are set automatically after each registration. 4. Mailboxes are created on each domain via Google Workspace or Zoho API. 5. Dashboard shows all managed domains with authentication status and deliverability health. 6. Mailbox credentials export in a format compatible with Instantly.ai and SmartLead. Stack: Next.js 14, Supabase, registrar API (Namecheap or Cloudflare), Google Workspace/Zoho API, Razorpay Rs3,999/month. Deploy: Vercel. Help me step by step: 1. Walk me through the registrar reseller account setup needed before writing any code. 2. Build the domain registration and DNS automation first. 3. Build the mailbox creation flow after DNS is confirmed working. 4. Build the dashboard with authentication status monitoring per domain. 5. Build the Instantly.ai/SmartLead export format. 6. Add the email warmup scheduling. 7. Wire up Razorpay. Keep explanations short and India-context aware. Flag clearly that registrar reseller account and mail provider API access are prerequisites needed before the first line of code. Push me to ship the smallest working version first. If I get stuck, tell me to ask @buildwithkanhaa.