[horde] Pass horde username to REMOTE_USER

[Toby Johnson]

I would like to integrate the web UI for my DSPAM install into my Horde 
setup in Plesk. My users probably won't use Horde as their primary email 
tool, so I'm not interested in deep integration, but I would like for 
them to be able to log in once to Horde and have DSPAM recognize them as 
well.

I can add a link to DSPAM in the sidebar, but DSPAM requires that the 
username be passed into the REMOTE_USER environment variable, as if HTTP 
Basic Authentication were used. I'm handy enough with Perl (which the 
DSPAM cgi is written in) so I could change this if necessary, but how 
best to do this so that the username is preserved as the users interact 
with the system?

The options I see are:
* somehow have Perl read the PHP session info
* have PHP call the DSPAM cgi itself, and display the output

The second option shouldn't be too difficult, but is there something I'm 
missing or some easier way to do this?