Error 503: Valid RCPT Command Must Precede Data [Fix]

Verify the email before resending to eliminate the error

3 min. read

Updated onOctober 4, 2023

updated onOctober 4, 2023

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Key notes

If you encounter the error message503 valid rcpt command must precede data, it usually means there’s a problem with the recipient (RCPT) command during SMTP (Simple Mail Transfer Protocol) communication.

Many email senders usingSMTP servers like Outlook 365 (Office 365)often encounter this error. So, in this guide, we walk you through the best solutions.

Why do I get the 503 valid RCPT command must precede data in Outlook?

There are a few things that will trigger this error in Outlook, including the following:

How do I fix the 503 valid rcpt command must precede data error?

Before you proceed with the solutions in this guide, do the following:

However, if you are unsuccessful after using the above pre-solutions, proceed to more detailed fixes below.

1. Configure the SMTP Authentication

2. Check Mailbox capacity

3. Check the email address

The email address you used in theFromfield is visible to the recipient when you send an email. Using a different email address than the one in your outgoing mail settings may lead to authentication problems and error 503.

Also, it’s important to note that using special characters, such as apostrophes, in email addresses can result in email transmission issues and potentially trigger the Outlook 503 error. To ensure accuracy, you should review and eliminate any special characters or symbols in the recipient’s email address.

4. Fix corrupt PST file

If the Outlook PST file is damaged, you might encounter the error 503. So you can use an advanced PST file repair software like Stellar Repair for Outlook.

We have written a comprehensive guide on using this tool tofix your bad PST files.

With the fixes discussed, you should have successfully fixed the 503 valid RCPT command must precede data error.

Other readers would love to know what worked for you, so please leave us a note in the comments section below.

Error 503: Valid RCPT Command Must Precede Data [Fix]#

Why do I get the 503 valid RCPT command must precede data in Outlook?#

How do I fix the 503 valid rcpt command must precede data error?#

1. Configure the SMTP Authentication#

2. Check Mailbox capacity#

3. Check the email address#

4. Fix corrupt PST file#