# What does the error '503 valid RCPT command must precede DATA' mean?

```markdown
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description: 'Hashtags: #Authentication #SMTP'
---

# What does the error "503 valid RCPT command must precede DATA" mean?

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

Here 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, meaning it has not exceeded its space limit. You can check 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 SSL encrypted connection.
4. Verify that your email account is correctly configured in your email client.
5. Enable SMTP authentication: In the SMTP outgoing 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 in: **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 to repair it or consult a technician to attempt it.
```


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