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What does the error “503 valid RCPT command must precede DATA” mean?

Hashtags: #Authentication #SMTP

The error 503 valid RCPT command must precede DATA is a problem that occurs in Outlook and other mail clients. It can be caused by various factors.

Below are some possible solutions:

  1. Remove any non-alphabetic characters, such as apostrophes ('), quotes (') or others, from the subject of the email you are sending

  2. Check that your email account is not full, i.e., that it has not exceeded its storage limit. You can review this in your cPanel. Keep in mind that avoiding leaving a copy of your messages on the server will help you save a lot of space in your email account

  3. Use a different SMTP port: you can use the alternative port 587 without encryption or 465 with an SSL encrypted connection.

  4. Verify that your email account is configured correctly in your mail client.

  5. Enable SMTP authentication: In the outgoing SMTP server, enable the option “My outgoing server requires authentication”. Check the option “Use the following credentials” and provide your email and the password assigned to that email account. Don’t forget to enable Outlook to remember your password in this option.

    You can find this at: Tools / Accounts / Account Properties and in the email account check More Settings / Advanced Properties. There you will find the checkbox “My server requires authentication”.

  6. Outlook PST file: Sometimes the 503 error occurs if you have a corrupt PST file. Try repairing it or consult a technician to attempt it.