𝗕𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝗔 𝗠𝘂𝗹𝘁𝗶 𝗧𝗲𝗻𝗮𝗻𝘁 𝗘𝗺𝗮𝗶𝗹 𝗦𝘆𝘀𝘁𝗲𝗺

𝗕𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝗔 𝗠𝘂𝗹𝘁𝗶-𝗧𝗲𝗻𝗮𝗻𝘁 𝗘𝗺𝗮𝗶𝗹 𝗦𝘆𝘀𝘁𝗲𝗺

You need a system for many clients. Each client needs their own domain.

You think Resend handles the data. It does not.

Resend Segments lack API filtering. You are unable to filter users by a plan or tag via API.

The working pattern is simple. Use Resend for delivery. Use your own database for everything else.

Your stack:

• FastAPI backend.
• PostgreSQL or SQLite database.
• Resend for domain checks and sending.

Your flow:

• Save customers and domains in your DB.
• Store contacts and tags in your DB.
• Filter your list in Python.
• Send emails in batches of 100.
• Use webhooks for bounces.

Three tips for you:

• Poll DNS verification every 30 seconds.
• Build auto-unsubscribe logic to save your account.
• Mock the Resend service for fast tests.

Resend is a sending engine. It is not a CRM. Own your contact layer to keep control.

Source: https://dev.to/srinivasa_rao/building-a-multi-tenant-email-system-with-fastapi-and-resend-what-the-docs-dont-tell-you-2lfo Optional learning community: https://github.com/srinivaspavuluri/resend-fastapi