Outlook Error – 503 Vaild RCPT command must precede DATA

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Two things will cause this issue.

  1. Email quota size full.
  2. SSL not setup correct.

Follow the steps below:

  1. Open outlook
  2. Go to Tools/Email Accounts
  3. Select the Account 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.

Now try sending an email in Outlook using the domain account.

Error 503: Valid RCPT command must precede DATA