The paperclip shows you that an Outlook e-mail message has an attachment.
Attachments in e-mail messages are one of the most common ways that your computer can "catch" a virus. Sometimes just opening the message can trigger the virus. As you can see in the picture on the left, it's easy to tell if a message has an attachment — it comes with a paperclip.
A new virus could have been released since your antivirus software was last updated. So always be very wary of attachments.
Be especially suspicious if the message is from someone you don't know (or aren't expecting to hear from), or if the subject line is strange.
If you are concerned that the message is infected, you can always send an e-mail message to the sender and ask for confirmation before opening it. If the message does turn out to be viral, delete it without opening it — and then delete it from your Deleted Items folder.
Tip To delete the message completely in one quick step, press SHIFT+DELETE.