Sending Email

Wasmer Edge provides built-in outbound email through the standard sendmail interface. This means your application can send transactional emails — password resets, notifications, welcome messages — without configuring an external SMTP server or a third-party email service.

To get started, you only need to enable the feature in your app configuration and redeploy.

Enabling Email

Email sending is disabled by default. Add enable_email: true to your app.yaml and redeploy:

kind: wasmer.io/App.v0
owner: my-account
name: my-app
package: .
 
enable_email: true

wasmer deploy

That’s it — once the app is redeployed, Wasmer Edge will make a sendmail binary available to your application.

PHP Applications

PHP’s built-in mail() function delegates to sendmail under the hood, so enabling the feature in app.yaml is typically all that’s required. Existing code that calls mail() will work without any changes:

<?php
$ok = mail(
  'user@example.com',
  'Welcome',
  "Thanks for signing up.\n"
);
 
echo $ok ? 'sent' : 'failed';

All Other Languages and Frameworks

For non-PHP applications, you interact with email through the sendmail command, just as you would on any Unix system.

1. Add the sendmail dependency

Include the sendmail/sendmail package in your wasmer.toml:

[dependencies]
"sendmail/sendmail" = "*"

2. Send an email

The sendmail binary reads a message from standard input. Use the -t flag to extract recipients from the message headers:

printf 'To: user@example.com\nSubject: Test message\n\nHello from Wasmer Edge.\n' \
  | sendmail -t

To set the envelope sender explicitly, add the -f flag:

printf 'To: user@example.com\nSubject: Test message\n\nHello from Wasmer Edge.\n' \
  | sendmail -f no-reply@example.com -t

Using a framework’s sendmail transport

Many web frameworks offer a sendmail transport as an alternative to SMTP. If yours does, point it at the sendmail binary and no further Wasmer-specific configuration is needed. A few examples:

• Django — set EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend' or use a sendmail backend package.

Rate Limits

Email sending is available on all plans. The free tier includes a limited sending allowance; paid tiers offer higher quotas. See the Wasmer pricing page for current plan details and limits.

Related

• App Configuration — enable_email