Spammers and hackers have found new ways to harm Outlook users.

WORKAROUND

Both Outlook and Outlook Express are unable to handle e-mails with improperly formatted message-ID headers or e-mails with just receive headers. See the examples below:

Emails like these are sent to 'abuse' or 'break' Outlook.

They do not contain any mail body or subject or from/to headers.

The messages do not violate RFC standards, which is why they are able to get past the RFC822 content filter in Icewarp Mail Server. Icewarp is compliant with all RFC standards and once a standard is set for filtering these types of messages our developers will adjust the core product to filter out these types of e-mails by default.

The messages are designed to affect Microsoft Outlook and Outlook Express. Other e-mail clients can download these messages without problems. Icewarp WebMail can display these e-mails, along with Mozilla, Netscape, The Bat! etc.

Once a message is in the user's mailbox on the Icewarp server it needs to be removed before the user can continue to use Outlook. You can either go into WebMail and delete the message or go to the Icewarp working directory and delete the message from the<Icewarp>\mail\domain\user\ directory.

Microsoft have addressed this problem and released an update. You can see more information here.

To stop these messages from getting to your Outlook users, you will need to build a content filter in your Icewarp mail server to block them.

When setting up these content filters you should move them to the top of the filter order so that these messages can be filtered as soon as they come in.

Missing Information filter

This content filter is for messages where the following mail headers are missing: [To:], [Cc:], [Date:], [From:], [Subject:]. Then the action command specifies to delete the message. The regular expression is set to '.+' ? it means at least one sign.