[imp] logon already filled out with a username?

[Marcus Frischherz]

Hi!

I am using imap authorization via imp for horde. This works fine. 
However, quite often, but not always, the logon screen has one username 
filled in. First I thought that I had used this username (it is not 
mine) once before and it is stored in a cookie, but I noticed now, that 
whenever imp is filling out the username, it is using this particular 
username, and even if it is the very first time my horde/imp site is 
used from a computer. So it cannot be stored in a cookie, but must be 
sent from the server. How can I turn this off, it is a slightly unsecure 
behavior. Anyone pointing his browser at my site gets the logon screen 
with a valid username presented.

thanks,

Marcus