Here's how the Looping Protection tab of the Email Service Properties dialog box looks like:




You can use this tab to configure the way the application detects closed loops. A loop may occur, for instance, when you set up an autoresponder than sends a message in response to any message sent to the autoresponder's email address. Consequently, the following situation might arise:

1. Someone sends an email to your address and then lefts their office and sets up an autoresponder on their machine.
2. The email is received by your autoresponder and a message is sent in response.
3. The response message is received by their autoresponder and, if their autoresponder doesn't detect the loop it sends a message to your address.
4. The message is received by your autoresponder and it sends the response message again.

And so on...

In order to make sure that the situation described above doesn't happen, use the slider to set the protection level to at least Normal.

There are three protection levels:

• No protection.
• Normal protection level. Messages with X-Loop header field set are automatically ignored by the application. Also, the application uses a custom header field to check for loops. This basic protection level should be sufficient in most cases.
• High protection level. Supports methods of normal protection level plus the subject is modified to include a unique ID. Any message whose subject contains an ID generated within past 48 hours is assumed to be causing a loop.

You can also configure a custom protection level.

Additionally, you can mark the Redirect ignored messages to a separate email address to have messages that are suspected of causing a loop to be forwarded to an email address you specify.

Mark Remove ignored message from the server if you would like the ignored message to be removed from the POP3 account or clear it if you want them to be left on the server. Either way, they will not be downloaded again by this email service but you may choose to leave them on the server if you want to download the messages using another email client.

Note that this tab is not available in the Standard Edition.