Error 503 Valid RCPT: how to fix it step by step
Description: Do you see the error "503 Valid RCPT command must precede DATA"? We explain why it happens and how to fix it easily.
What does this error mean and why does it appear?
This error message appears when you try to send an email from your client (Outlook, Thunderbird, Apple Mail, etc.) and the server rejects the send with this message:
"503 Valid RCPT command must precede DATA".
In simple terms, the server is telling you:
"I need to know who the email is addressed to (RCPT TO) before you send me the content (DATA)."
This normally happens because of an incorrect configuration in the email client. The good news is there's a quick fix!
How to fix the error step by step
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Verify that you're authenticating to send emails
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In your email client, find the outgoing server (SMTP) settings.
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Make sure the option is enabled:
"My server requires authentication". -
Use the same credentials as your incoming email (email username and password).
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Check the SMTP port and encryption type
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The values recommended by Bacan.com are:
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SMTP Server: mail.yourdomain.com
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Port: 465 (with SSL) or 587 (with STARTTLS)
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Encryption: SSL or STARTTLS (depending on the port)
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Make sure these values are correctly configured.
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Check the recipient's address
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Sometimes the error can arise if the recipient's email address is misspelled or invalid.
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Verify it has the correct format: example@domain.com
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Avoid using multiple recipients without separating them correctly
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If you're sending to multiple people, make sure to separate them with commas or semicolons depending on your email client.
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You can also use the CC or BCC fields correctly.
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Try sending yourself a test email
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This helps verify if the error persists when using a valid and known destination address.
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Useful tips
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If you recently changed your email password, make sure to update it in your client too.
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Update your email application to the latest available version.
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You can try using Webmail (from your DirectAdmin or cPanel control panel) to verify if the problem only occurs in your local client.
Remember
The error 503 Valid RCPT command must precede DATA may seem complicated, but in most cases it's resolved with a simple authentication and SMTP configuration check.
If the problem continues after following these steps, don't hesitate to contact our technical support team from your client area or via ticket. We're here to help.
Also check our other tutorials on email configuration for different devices and clients.