Today I will show you how to resolve the error “503 command RCPT must precede DATA”.
When sending email, if you receive an immediate bounce-back, such as the following:
Subject: RE: XXXXXX - DATE/DATE/DATE
The following recipient(s) could not be reached:
‘User Name’ on DATE/DATE/DATE
503 valid RCPT command must precede DATA
This error happens if SMTP server requires authentication is not enabled.
This means that before sending email, you must set up authentication, which is required by your mail server.
If you are trying to send mail from your mail client, please ensure that the option SMTP server requires authentication is enabled and the same settings are used for incoming mail.
Please follow the relevant instructions below to verify SMTP Authentication is enabled.
Microsoft Outlook (or Outlook Express)
1) Open Microsoft Outlook and from the top menu select Tools > Accounts.
2) Choose the Mail tab and then click once on the appropriate email account from the list and click Properties.
3) The account properties will appear. Choose the Servers tab and then check the box “My server requires authentication”.
4) The Servers tab also includes an option for ”Secure Password Authentication”. This is not the same as SMTP Authentication and it should be unchecked.
4) Click on the Settings button. In the ‘Outgoing Mail Server’ dialog box, make sure “Use same settings as my incoming mail server” is selected.
5) Save and close the properties by clicking OK. All done!
1) Open Thunderbird and from the top menu select Tools > Account Settings…
2) At the bottom of the list click on ‘Outgoing Server (SMTP)’, and then click once on the appropriate email account from the list and click Edit.
3) The SMTP server settings will appear. There will be an dropdown menu for Authentication Method with five options in it. If the option ‘No Authentication’ is selected then change it to ‘Password, transmitted insecurely’ and this will enable SMTP Authentication.
4) Make sure the User Name box contains your FULL email address. Unlike other email programs, Thunderbird doesn’t ask for your password at this stage, but it will ask the first time you try to send an outgoing email.
5) Save and close the settings by clicking OK. All done!
1) Open Apple Mail and in the top menubar click on Mail > Preferences > Accounts.
2) Click once on the appropriate email account from the list and click Account Information. Click on the “Outgoing Mail Server (SMTP)” pulldown list and select “Edit SMTP Server List…” from the bottom of the list.
3) Click on Advanced and make sure Authentication is set to ‘Password’. This will enabled SMTP Authentication.
4) Make sure the User Name box contains your FULL email address and make sure your Password is correct (as specified in your control panel).
5) Save and close the advanced settings by clicking OK, then close the Preferences window by clicking on the X in the upper left hand corner of the window. All done!
Apple iPhone or iPad
1) Tap on ‘Settings’ from your main screen
2) Tap ‘Mail, Contacts, Calendar’ button
3) Tap on YOUR EMAIL ACCOUNT
4) Scroll down to the ‘Outgoing Mail Server’
5) Make sure the User Name box contains your FULL email address and make sure your Password is correct (as specified in your control panel).
6) Make sure Authentication is set to ‘Password’. This will enabled SMTP Authentication.
7) Save and close the settings. All done!
Please let me know if you have any further issue. 🙂
My name is Shashank Shekhar. I am a Software Engineer, currently working in one of the leading web-hosting companies in India. I am having 2 years of experience in Linux Server Administration.
I love to work in Linux environment & love learning new things.
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