In general, the key to survival of enveloped viruses is 
the exposure to light and air.  Most enveloped viruses 
lose infectivity after exposure to these denaturing 
conditions.  That is why 3 to 24 hours can be a 
reasonable period of viability.  If the virus is contained 
in sealed package, within a mucus blob, or similar 
protected environment, the virus can have extended 
infectivity.  The key to not becoming infected by a 
package is to wash your hands after touching 
transshipped packages.  A little soap and water go a 
long way to reduce or eliminate the infectivity of these 
viruses.

rallihir