It's a link to an iCalendar .ics file, a text file using a standard syntax
for calendar information exchange. You can create your own such files with
Outlook's File | Save As command.

Signature
Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I have recieved emails in the past, in which a "link" was there that I
>could
[quoted text clipped - 4 lines]
>
> Thanx