We Replaced Resend With a Custom Email System Built in 2 Hours

The Problem

Resend costs $20/month. For many small teams, that is money spent on a tool they only partially use. We asked: can we rebuild the core functionality ourselves?

What We Built

A replacement for Resend using Python, Flask, and SMTP. The system handles transactional email delivery, basic template rendering, and send logging — covering the 80% use case for small teams.

How We Did It

Stack: Python, Flask, SMTP

Estimated time: 135 minutes

Build Steps

[done] Step 1: Scaffold Flask app and SMTP connection layer (Python, Flask, SMTP) – 20min

[done] Step 2: Implement send_email() with template variable substitution (Python, Jinja2) – 25min

[done] Step 3: Add send logging to SQLite (Python, SQLite) – 20min

[done] Step 4: Build REST endpoint POST /send (Flask) – 15min

[done] Step 5: Write validation layer and error handling (Python) – 20min

[done] Step 6: Test against live SMTP relay (SMTP, Python) – 15min

[done] Step 7: Document and package (Python) – 20min

Results

Steps completed: 7/7

Total build time: 135 minutes

Completion: 100%

Verdict: COMPLETE

Build vs Buy

Buy (Resend) Build (Custom) Cost $20/month Time investment only Stack Managed SaaS Python, Flask, SMTP Setup Time Minutes 135 minutes Ongoing Cost $20/month $0 (self-hosted)

Limitations of the Rebuild

No hosted deliverability infrastructure (you need your own SMTP relay)

No open/click tracking without additional build work

No GUI dashboard – API and logs only

Not suitable for high-volume bulk email without relay configuration

Verdict

The rebuild is complete. We successfully replaced Resend with a custom solution built in 135 minutes using Python, Flask, SMTP. The ongoing cost is $0.

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Want us to build this for you?

We help small teams replace expensive SaaS tools with AI-assisted custom builds. If you are paying for a tool you barely use, we can probably rebuild it for less.

Get a free rebuild assessment

Free giveaway: Every month we give away one free rebuild to a qualifying team. Reply to this post or DM us to enter.

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