Resolving the '550 sender verify failed' error message

When sending e‑mail, you may encounter the SMTP error:

550 Sender verify failed

This error indicates that the mail server could not verify the sender’s address. It is a common anti‑spam measure known as Sender Address Verification (Callback Verification).

Causes

• The sender e‑mail account does not exist in cPanel.

• The domain’s MX records are misconfigured in cPanel.

• Example: You add a parked domain, addon domain, or reseller account, but the MX records point to an external provider (like Google Workspace or Microsoft 365) without updating cPanel accordingly.

Resolution Steps

1. Verify the E‑mail Account Exists

• Log in to cPanel → Email Accounts.

• Ensure the account you’re using actually exists.

• Confirm you’re using the correct username (full e‑mail address) and password for SMTP authentication.

2. Check MX Records

• If your domain uses a remote e‑mail provider, update MX entries in cPanel:

  1. Log in to cPanel.

  2. Go to Email → Remote MX Wizard.

  3. Select the domain.

  4. Configure it to use the remote provider (e.g., Google, Microsoft).

3. Adjust Mail Exchanger Settings

• In cPanel → Email Routing, ensure the domain is set to:

  • Remote Mail Exchanger if using external mail servers.

  • Local Mail Exchanger if using cPanel’s mail server.