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Transactional Email

FastSvelte sends transactional email — verification, password reset, and organization invitations — through a pluggable provider. Pick one of Resend, SendGrid, or Azure Communication Services, or use the stub provider in development.

Choosing a Provider

Set FS_EMAIL_PROVIDER in backend/.env to one of: resend, sendgrid, azure, or stub.

For the providers you don't use, clean up all three places:

  1. backend/pyproject.toml — delete the two package lines you don't need, then run uv sync:

    "azure-communication-email>=1.1.0",  # FS_EMAIL_PROVIDER=azure
"resend[async]>=2.30.1",             # FS_EMAIL_PROVIDER=resend
"sendgrid>=6.12.5",                  # FS_EMAIL_PROVIDER=sendgrid

    cd backend && uv sync

  2. backend/.env — remove the env vars for the unused providers.

  3. backend/app/config/settings.py — remove the corresponding settings fields (e.g. resend_api_key, resend_sender_address, resend_sender_name).

Resend

A modern email API with a generous free tier — recommended for most new projects.

  1. Sign up at resend.com and create an API key at resend.com/api-keys.
  2. Add and verify your sending domain at resend.com/domains.
  3. Configure backend/.env:
FS_EMAIL_PROVIDER="resend"
FS_RESEND_API_KEY="re_your-resend-api-key-here"
FS_RESEND_SENDER_ADDRESS="noreply@yourdomain.com"
FS_RESEND_SENDER_NAME="Your App Name"

SendGrid

FS_EMAIL_PROVIDER="sendgrid"
FS_SENDGRID_API_KEY="SG.your-sendgrid-api-key-here"
FS_SENDGRID_SENDER_ADDRESS="noreply@yourdomain.com"
FS_SENDGRID_SENDER_NAME="Your App Name"

Verify your sender email/domain in the SendGrid dashboard first.

Azure Communication Services

For Azure-based deployments:

FS_EMAIL_PROVIDER="azure"
FS_AZURE_EMAIL_CONNECTION_STRING="endpoint=https://..."
FS_AZURE_EMAIL_SENDER_ADDRESS="noreply@yourdomain.com"

Development (Stub)

For local development without sending real email:

FS_EMAIL_PROVIDER="stub"

Emails are logged to the backend console instead of sent — look for [STUB EMAIL] blocks containing verification and invitation links.

Testing

curl -X POST http://localhost:8000/password/forgot \
  -H "Content-Type: application/json" \
  -d '{"email": "test@example.com"}'

Troubleshooting

  • Not sending — verify the API key, confirm the sender domain/address is verified with the provider, and check the backend logs.
  • Production — set up SPF/DKIM for your sending domain.