BulletProof FTP Server has the ability to serve files on your Mapped Network Drive via FTP. But you will need to add some special parameters to make sure that the credentials for the mapped drive are saved and the connection is toggled as persistent.
This is best done via the command-line (CLI) using the NET.EXE USE command.
Take the following example:
c:> %SystemRoot%\system32\net.exe use h: \\myserver\myshare /user:myusername /persistent:yes
In this example we are mapping drive-letter “H:” to a computer named “myserver” with a share-name of “myshare”, where the credentials needed to login to the machine are specified as “myusername” (if you were part of a domain, it would be “mydomain\myuser). The “/persistent:yes” instructs Windows to reconnect the drive at login.
Full Docs on the NET.EXE USE command:
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/net_use.mspx?mfr=true
Microsoft Windows, by default, disconnect network-drives after X minutes of inactivity. Remapping the drive is done quickly and usually without any interruption. However if you have any problems, it’s recommended that you increase the default 600 seconds (10 minutes) to a larger number:
Mapped Drive Connection to Network Share May Be Lost