[Solved] 503 valid RCPT command must precede DATA - Outlook Error

I you are getting the following error in Microsoft Outlook, your outgoing email server is telling you that Outlook has not given the proper credentials to the server; your current account settings are not properly authorizing you to send email through that account. You may receive an error similar to this:

The following recipient(s) could not be reached:
'user@somedomain.com' on 10/10/2010 12:30
503 valid RCPT command must precede DATA

Usually this is a simple fix. You simply have to set up your account in Outlook to give your mail server the authorization that it requires.

In the next few sections, I will show you how to do that in various versions of Outlook. There are other solutions further down, if the simple fix does not work.

This is the "Simple Fix" for error code 503 In Outlook 2003:

• Click on the Tools menu;
• Click on "View or change existing e-mail accounts";
• Click the [Next] button;
• Click on the account that was trying to send the email;
• Click the [Change] button;
• Click the [More Settings ...] button;
• Click the Outgoing Server tab at the top;
• Put a check beside "My outgoing server (SMTP) requires authentication";
• Click on "Use same settings as my incoming mail server";
• Click [OK];
• Click [Next];
• Click [Finish];

This is the "Simple Fix" for error code 503 In Outlook 2007:

• Click on the Tools menu;
• Click on "Account Settings...";
• Click the E-mail tab at the top;
• Click on the account that was trying to send the email;
• Click on the [Change...] icon;
• Click the [More Settings ...] button;
• Click the Outgoing Server tab at the top;
• Put a check beside "My outgoing server (SMTP) requires authentication";
• Click on "Use same settings as my incoming mail server";
• Click [OK];
• Click [Next];
• Click [Finish];
• Click [Close];

This is the "Simple Fix" for error code 503 In Outlook 2010:

• Click on the File menu;
• Click on large "Account Settings...";
• Click on small "Account Settings..." dropdown;
• Click the E-mail tab at the top;
• Click on the account that was trying to send the email;
• Click on the [Change...] icon;
• Click the [More Settings ...] button;
• Click the Outgoing Server tab at the top;
• Put a check beside "My outgoing server (SMTP) requires authentication";
• Click on "Use same settings as my incoming mail server";
• Click [OK];
• Click [Next];
• Click [Close] on the Account Test window, if it pops up;
• Click [Finish];
• Click [Close];

If none of the above simple fixes works for you, see if any of these tips are useful:

• Press the F9 key on your keyboard to check for new mail before trying to send. Some accounts authorize outgoing mail via a check for incoming mail. You may then be authorized to send mail for 30 minutes or so.
• Apostrophes in account names (o'neil@somedomain.com for example) can also cause this error under some circumstances. If the email address is under your control, remove the apostrophe to avoid the error for yourself and others.
• If you were replying to a message, and have multiple accounts set up in Outlook, keep in mind that Outlook will reply through the account the original mail was sent to; so if the simple fixes above did not work when applied to your default account, try applying the same fix to any other accounts you have set up.
• If the problem persists, contact your email provider and ask for support; they can check your account and may find an issue that can be fixed and get you back up and running!