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WHMCS, cPanel, and Exim SMTP Relay

Use this guide when a hosting stack should send outbound mail through Mailtarget while the application continues to use SMTP.

Mailtarget settings​

Host: smtp.mtrgt.net
Port: 587
Encryption: STARTTLS
Username: smtp_mt_injection
Password: <api_key with Send via SMTP permission>

WHMCS​

In WHMCS mail settings:

  1. Select SMTP as the mail provider.
  2. Set host to smtp.mtrgt.net.
  3. Set port to 587.
  4. Enable TLS or STARTTLS.
  5. Set username to smtp_mt_injection.
  6. Set password to a Mailtarget API key with Send via SMTP permission.

Exim relay outline​

For Exim-based systems, configure a smarthost route to smtp.mtrgt.net::587, enable authentication, and require TLS. Exact file paths vary by cPanel and Exim version, so apply changes through the supported WHM interface when possible.

Validation​

Send a message to an external mailbox and confirm:

  • Exim accepts the message locally.
  • The Mailtarget relay accepts the message.
  • The recipient domain receives the message.
  • Mailtarget records delivery, bounce, or delay events.