Error 503: Valid RCPT Command Must Precede DATA (Outlook 2016)

May 2, 2019

The following article was written by a member of our community. If you’d like more articles like this, let us know!

The “Error 503: Valid RCPT command must precede DATA” can occur when you try to send emails. This error means that your email server did not correctly authenticate your SMTP (outgoing mail) connection.

Possible Reasons

There are two possible and most common reasons for this behavior:

1) You need to check email first before sending an email (checking email first is one of the ways email provider can do to manage the security of your email account)

2) Your email client software isn’t correctly set up for SMTP Authentication


Check Email Before Trying to Send

When you first open your email client, it usually automatically checks for new emails first. However, if you try to send an email after about 30 minutes and you see this error message, check your email for new messages first and you’ll then be able to send an email if this is the problem (most common with Outlook).

More often, error in question tells you that you need to set up SMTP Authentication in your email client software.

How To Set SMTP Authentication

Setting up SMTP Authentication in your email client software requires you to edit your email account SMTP (outgoing mail) settings. You need to add your email address and password to the SMTP (outgoing) settings, and you’ll no longer receive error 503 messages.

Setting up SMTP authentication depends on the email software you use.

Outlook 2016

Here’s how you can configure it in Outlook 2016 software:

  • Open Outlook 2016
  • Click the File menu and select Account Settings –> Account Settings
  • In the Account Settings window, select the email account you wish to set up and click the Change button
  • In the Change Account window, click the More Settings option
  • From the More Settings window, select the Outgoing Server tab
  • Check My outgoing server (SMTP) requires authentication option
  • Select Use same settings as my incoming mail server option
  • Open the Advanced tab
  • In the Advanced tab, set the Outgoing server (SMTP) port to 465. In Use the following type of encryption drop-down, select SSL
  • Click OK
  • In the Internet E-Mail Settings window, click Next
  • Click Finish

Leave a Reply