Anyone have a problem in Outlook when trying to send an email that says '503 Valid RCPT command must precede DATA'? It's a total pain.
Other websites said to do things that didn't solve it, including:
1. Clicking receive to receive before sending. Still get 503 RCPT error.
2. Checked 'My outgoing server (SMTP) requires authentication. Still get 503 RCPT error.
3. I changed Outgoing server (SMTP) from 25 to 26 (if hosted by Linux server), as per instructions in cpanel when configuring mail. Still get 503 RCPT error.
503 Valid RCPT command must precede DATA - what a pain!
Alas! Here's what solved it: changing from "Log on to incoming mail server before sending mail' to 'Use same settings as my incoming mail server'.
So, the folks giving the advice to log on to incoming mail server before sending mail was wrong- that actually CAUSED the Outlook error!
If you have Outlook 2010, you probably have a nightmare trying to navigate through its menus, which they hid from everyone in that version. Instead of clicking once or twice, visible directly from the drop down menu, you have to click multiple times and its found in an unlikely place.
Here's how to change email settings in Outlook 2010:
1. At top left, click File tab
2. Click Account Settings in the middle of screen, then click it again (stupid navigation)
3. Select your email account from list, then when highlighted, click Change... above
4. At bottom right, click More Settings...
5. Click Outgoing Server tab at top
6. Make sure 'My outgoing server (SMTP) requires authentication is checked
7. Make sure 'Use same settings as my incoming mail server' is checked
8. That should solve your Outlook '503 Valid RCPT command must precede DATA' error. If not, then I'd ask tech support for your web host provider.
Hope that helps someone and saves hours like it could have for me.