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503 Valid RCPT Command Must Precede DATA

This error normally appears when your email program tries to send mail without authenticating correctly.

The mail server is rejecting the message because it has not confirmed that you are allowed to send through it.

Fix the Error

  1. Open the account settings in your email program.
  2. Find the outgoing mail server or SMTP settings.
  3. Make sure SMTP authentication is enabled.
  4. Use the same email address and password that you use for the mailbox.
  5. Save the settings.
  6. Try sending the message again.

What the Setting May Be Called

Different email programs use different wording.

Look for an option such as:

  • My outgoing server requires authentication
  • My server requires authentication
  • SMTP authentication
  • Authenticate senders
  • Use same settings as incoming mail server

If It Still Does Not Work

Check that the outgoing mail server, username, password, port, and encryption settings are correct.

If you are not sure what settings to use, check the email setup details in your 4UHosting customer account or open a support ticket.