PC users have been warned to look out for a new mass-mailing Windows virus named 'MiMail', which is spreading rapidly.

Victims receive an email disguised as a message from the user's domain name 'administrator' - the person or organisation that controls ownership of email addresses.

"I would like to inform you about important information regarding your email address. This email address will be expiring. Please read attachment for details," the message reads.

The virus is in the attachment, named message.zip. Email security company MessageLabs said the virus creates a file on the recipient's computer and attempts to run it before searching the hard disk to harvest email addresses from the victim's computer.

Users should ensure that their antivirus software is up to date.