Error 503: Valid RCPT command must precede DATA (Apple Mail)

The “Error 503: Valid RCPT command must precede DATA” happens when sending email. It’s telling you that your SMTP (outgoing mail) connection was not properly authenticated by your email server.

The two most common causes for this error are:

  • Your email server requires you to check email first before sending email (checking email first is one way your email provider manages the security of your email account).
  • Your email client isn’t set up for SMTP Authentication.

Checking email before sending

When you first open your email client, it automatically checks email first. However, if you attempt to send email after about 30 minutes and you see this message, simply check your email for new messages. You’ll then be able to send email if this is the problem.

More often, Error 503 tells you that you need to set up SMTP Authentication in your email client.

Setting up SMTP Authentication

Configuring SMTP Authentication in your email client requires you to edit your email account SMTP (outgoing mail) settings. Add your email address and password to the SMTP settings and you’ll receive no more Error 503 messages.

How you set up SMTP Authentication depends on the email client you use. Here’s how to set it up in Apple Mail:

  1. Open Apple Mail.
  2. Open the Mail menu and select Preferences.
  3. In the Preferences window, click Accounts.
  4. In the Accounts pane, select the account you wish to update in the left panel, then click the Outgoing Mail Server (SMTP) drop-down and select Edit SMTP Server List.
  5. Select the outgoing mail server you wish to change and click the Advanced tab.
  6. Check Use Default Ports (25, 465, 587).
  7. Check Use Secure Sockets Layer (SSL).
  8. Make sure the Authentication drop-down is set to Password.
  9. Check that your username and password are correct.
  10. Click OK to save your settings.

If, for some reason, the above steps fail, please contact HostPapa Support for further assistance.

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