Backup email sender

A platform-level transactional sender that automatically carries email when the primary provider is unavailable, with no per-account setup.

What it is

A single-key adapter with a platform From identity that talks to Resend's HTTP API directly. It has no prerequisites in the provider catalogue — it is used automatically when the others cannot deliver.

Also called: Resend · fallback email · if Mailgun is down

See it
Backup email sender
Area
Integrations
Group
Email delivery
System
Resend
Solves
2 named problems
01The chain reaches Resend after the primary email provider skips or fails.
02The adapter posts to the Resend API with a 15-second timeout.
03A plaintext alternative is derived from the HTML, stripping style blocks first so CSS never becomes body copy.
The provider card from the catalogue: 'Backup email sender. Used automatically if the others are unavailable.' with no setup fields. Sample data — no customer information appears here.
How it works
  1. 1The chain reaches Resend after the primary email provider skips or fails.
  2. 2The adapter posts to the Resend API with a 15-second timeout.
  3. 3A plaintext alternative is derived from the HTML, stripping style blocks first so CSS never becomes body copy.
  4. 4A rejection is non-retryable because the provider saw the message.
Why we built it

The adapter's header is a full post-mortem of the day it stopped being an adapter: it delegated back into the dispatcher and 'the call graph closed into a loop... until the stack overflowed... The fix is for the adapter to actually be an adapter: it now speaks to Resend's HTTP API itself and imports nothing from the dispatcher that calls it.' The From note is practical: an unset identity 'falls back to Resend's shared sandbox sender, which still delivers but carries a much heavier rate limit.'

The problem
  • There was no second sender when the primary failed.
  • A recursive fallback crashed the process instead of delivering.
Sound familiar?
What you get
Transactional mail keeps flowing during a primary outage.
No setup required from the builder.
Plaintext alternatives are clean, not full of stylesheet text.

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