Error: 503 valid RCPT command must precede DATA
This may cause if the “My outgoing server (SMTP) requires authentication” option is disable in outlook or disk quota for email account is full.
To resolve this problem please follow below steps.
1. Enable SMTP authentication in your outlook email client:
Select My outgoing server (SMTP) requires authentication
- In Outlook, click File
- Click Account Settings > Account Settings
- Select your email account.
- Click Change…
- Click More Settings…
- Select the Outgoing Server tab
2. If SMTP authentication is already enabled then Check email account disk quota by login to cpanel/webmail. If email quota is full then you need to delete some unwanted mails and free up the disk space.
3. If all the settings are correct, then the Outlook profile might be corrupt. Re-adding the account in Outlook or repairing the Outlook PST file can fix the issue.
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