Email Error 503 Valid RCPT command must precede DATA

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Error: 503 Valid RCPT command must precede DATA

Your message did not reach some or all of it’s intended reciptients.

Subject: XXXXXX

The following receipient(s) cannot be reached:

‘Joe Blogs’ on DAY-MONTH-YEAR

503 Valid RCPT command must precede DATA


This error is usually received as an immediate bounced email when trying to send an email.


You must authenticate your mail email before trying to send. And in the case of Red Hippo’s mail servers as with most other hosting companies those credentials are usually the same as the incoming credentials.

To automatically do this, ensure that you check the “my server requires authentication” box in your email client and it will use the same sending credentials that it uses for receiving email.

If you’re using Microsoft Outlook then do the following:

  1. Go to Account Settings
  2. Click on Email
  3. Select the Mailbox in question > Change
  4. Click More Settings…
  5. Click Outgoing Server
  6. Check the My Outgoing Server (SMTP) Requires Authentication box
  7. Click the Use sames settings as my incoming mail server radio button to automatically do this
  8. You can click OK and continue as this should fix the error but if not
  9. In the same More Settings… area, click the Advanced tab
  10. Change the Outgoing server (SMTP) port from 25 to 587
  11. Click Ok and test your account settings again

If you are still having difficulty please contact Red Hippo Support and we’ll gladly assist.

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