503 This mail server requires authentication / 503 Valid RCPT command must precede DATA

503 Authentication Required / “Valid RCPT command must precede DATA” Errors

If you see these errors when sending mail to non-local addresses, it means your SMTP client isn’t authenticating before you attempt to send:

• 503 This mail server requires authentication
• 503 Valid RCPT command must precede DATA

Before sending, your mail client must prove your identity to the server. Here are the two most common ways to fix it:

1. “POP Before SMTP”

Some servers allow you to send for 30 minutes after you check (POP) for new mail.

1. “Get Mail” / “Check Mail” in your client.
2. Wait for the retrieval to complete.
3. Compose and send your outgoing mail.

2. SMTP Authentication (Recommended)

Most modern clients support “SMTP Authentication,” which logs you in automatically before sending.

1. Open your mail client’s account settings.
2. Find the SMTP (Outgoing) server settings for your account.
3. Enable “My outgoing server (SMTP) requires authentication.”
4. Select “Use same settings as my incoming mail server.”
5. Save and close settings.

Example: Microsoft Outlook

1. Go to File > Account Settings > Account Settings…
2. Select your account and click Change.
3. Click More Settings… > Outgoing Server tab.
4. Check “My outgoing server (SMTP) requires authentication” and choose “Use same settings as incoming mail server.”
5. Switch to the Advanced tab:
   • First try SMTP port 587 (TLS).
   • If that fails, try port 26 (non-SSL).
6. Click OK, then Next, then Finish.

Still Having Trouble?

If you continue to receive authentication errors, please verify:

• Your username is your full email address.
• Your password is correct (you can test it by logging in to Webmail).
• You’re using the correct server name: mail.yourdomain.com.

For further assistance, open a support ticket at https://support.indichosts.net/en/tickets/create/step1 .