If this is webmail you view through your browser, you need to adjust the
options of your webmail account to allow for the opening of attachments and
this location varies by service provider. You'll have to find out from them
how to gain such access. NOTE: some providers block all such access.
If you are using Outlook Express, go to Tools, Select Options, go to the
Security tab, remove the check from "Do not allow attachments to be saved or
opened that potentially might be a virus," click apply and ok.
NOTE: you should always save an attachment and scan it for viruses before
opening. You should realize most people get viruses from friends and people
they know as those individuals often don't realize they are infected.
Viruses usually propagate by sending themselves to all entries in the
address book of the person who has unwittingly executed the virus.