SMTP Authorization

When attempting to send mail through your account's SMTP server, the following error may occur:

 
The message could not be sent because one of the
recipients was rejected by the server...Protocol: SMTP,
Server response: 553 Sorry, that domain isn't in my list
of allowed rcpthosts (#5.7.1)...

This error is not isolated to one mail client and the result is always the same, the messages in the Outbox are not sent.

Explanation

Our servers are designed to allow only authenticated POP account users to send mail (i.e. the "send from" address must be an existent and authenticated POP account). This prevents spammers from sending untraceable messages through our SMTP server.

By default, email clients do not submit any login information for validation while sending mail, so you are not an authenticated user unless you check for mail, first. When there are messages waiting to be sent, mail clients try to send the messages first, and then check for new messages. This sequence is what generates the error.

Solution

Microsoft Outlook Express

Outlook Express has a user-specified setting which forces the software to submit login information when sending e-mail.

  • Select the Tools menu
  • Select Accounts...
  • Click on the Mail tab
  • Select your POP account from the list of mail accounts
  • Click on Properties
  • Select the Servers tab
  • Check the box that is labeled My server requires authentication
  • Click on OK to save this setting for that account
  • Click on Close to exit Accounts window
Please acquire the habit of always checking for new messages before sending any email. This is very quick to do, usually with only one mouse click.

Before trying to send mail with Outlook Express 6, click on the [Send/Recv] button