mailofly.dev Domain Error - Mailofly

When testing Mailofly without adding a custom domain, you can send emails using the shared testing domain onboarding@mailofly.dev (or test.mailofly.dev). If you encounter an error when sending via the test domain, review the constraints below.

Common Reasons for Errors

1. Sending to Unverified External Addresses

The default test domain is strictly sandboxed. You can only send test emails to the email address associated with your Mailofly account. If you attempt to send an email to any third-party recipient, the API returns:

{
  "statusCode": 403,
  "message": "You can only send to your own registered account email while using the test domain. Please add and verify a custom domain to send to external recipients."
}

2. Rate Limits on Shared Domains

Shared testing domains are subject to strict per-minute and per-day rate limits to protect reputation across all developing accounts.

Solution: Add Your Custom Domain

To send to any recipient without sandboxing restrictions:

Navigate to Domains in your Mailofly dashboard.
Click Add Domain and enter your domain name (e.g. yourcompany.com).
Add the generated DKIM, SPF, and MX records to your DNS provider.
Once verified, update your from address to match your verified domain (e.g. notifications@yourcompany.com).

Related topics

Errors Error 1010 Domain already registered Domain Mismatch SDKs

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