Build Week #1, Day 3:
Schedule and offload emails

Offload the sending of emails

Sending emails following a user action directly from an API Route is tempting but comes with many drawbacks:

• Your Email Provider might not scale as well as your Serverless Functions, resulting in reliability issues (rate limiting)
• Sending a lot of emails from Serverless Functions (without a Provider) might lead to IP Reputation issues
• Overall, sending email from an API might degrade the end-user performance (especially for compute-intensive rich emails)

For all those reasons, and especially when sending rich emails with Resend, offloading them to run in the background is a straightforward solution.

Get started in under 2 minutes by using our Resend x Next.js template, deployable on Vercel in one click.

Advanced scheduling of emails

Some emails need to be sent on very specific schedules, for example:

• Following a sliding billing window
• Following specific application triggers (ex: when a user reaches 100 logins)
• Following specific criteria (ex: email campaign)

Those scenarios greatly benefit from Defer's Epoque Scheduler while relying on Defer's Platform to scale thousands of executions.

See an example of a Monthly billing email schedule following a sliding window in our Resend x Defer guide.