[imp] Getting IMP to append virtual host to user@

[Eric Brown]

I have IMP and HORDE running on IIS6 (works perfect!) as a virtual subdomain for
all of my domains (webmail.mydomains.com). The virtual host settings work fine
(I have to add each server manually to the horde config files), but IMP
requires users to login via user at domain.com. How can I get the login to append
@domain.com based on what virtual host they came through if they do not do it
themselves?

Thanks :)