When attempting to send email you receive the following message in your mail client software:
"503 valid RCPT command must precede DATA"
You must check your email before trying to send email. Our mail servers requires authentication.
The mail servers are set to POP before SMTP as a security measure to prevent SPAM.
The mail server collects your IP address when you authenticate yourself with the POP server, and then permits SMTP relaying from that IP address for a short period of time.
Explanation of fix: Pop before smtp -- check your email for new mail before trying to send email.
1) Move anything in your Outbox to your Drafts folder.
2) With nothing in your Outbox, click Send/Receive.
3) After a successful Send/Receive, try sending an email from your drafts folder.
Long Term Fix (in Outlook Express)
1) Go to Tools/Email Accounts
2) Select the Account with the trouble and click Change
3) Click on More Settings
4) Click on Outgoing Server Tab
5) Click "Outgoing Mail Server (SMTP) requires authentication" and make sure "Use same settings as incoming mail server" is selected (see attached image)
6) Click on "Advanced Tab"
7) Set outgoing Port (SMTP) to 25 or 50 (50 is used for ISPs that block port 25 usage outside their own service).
8) Click Ok and then Test Account Settings
Long Term Fix (in Outlook 2003)
1) In Outlook, go to "Tools" then "Email Accounts".
2) Click "View or change existing e-mail account", then click "Next".
3) Select your account, then click "Change".
4) Click "More Settings".
5) Click the tab labeled "Outgoing Server".
6) Select "My outgoing server (SMTP) requires authentication", then select "Log on to incoming mail server before sending mail" at the bottom.
7) Click "OK".
8) Click "Next".
9) Click "Finish".
Long Term Fix (in Outlook 2007)
1) Open outlook
2) Go to Tools/Email Accounts
3) Select the Account with the trouble and click Change
4) Click on More Settings
5) Click on Outgoing Server Tab
6) Click "Outgoing Mail Server (SMTP) requires authentication" and make sure "Use same settings as incoming mail server" is selected (see attached image)
7) Click on "Advanced Tab"
8) Set outgoing Port (SMTP) to 26.
9) Click Ok and then Test Account Settings
If it fails on send then repeat starting from 7.
7) Click on Advanced Tab
8) Set outgoing Port (SMTP) to 465 (See attached)
9) Check the box Beside "The server requires an encrypted connection (SSL)".
10 ) Click ok and then Test Account Settings.
Long Term Fix (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.
You mail software may also be acting unreliably. In such cases we recommend removing the mail account from your mail software, restart your PC/Mac and then add the mail account back fresh.