Completed in IMP 5.

Needs to be a config setting, but not entirely this simple.  In HEAD, 
if the addressbook contains less than 200 entries, this entire address 
book is sent to the browser and the browser does the search entirely 
within browser-space.  In this situation, there should be no 
limitation on the number of characters so the config text needs to 
make this clear.

Simple brain-dead patch to limit searches to 3 characters or more.   
Unless we want to choose 3 characters for all installations, this 
should probably be implemented as a config setting for IMP.

This is an IMP issue

Currently when you go to compose a message if you have any 
addressbooks defined in Turba horde will attempt to do address 
completion when you start typing in the "to" field.  However, if you 
have a large LDAP or other directory server included in the list it 
will return enormous lists when you match on one or two characters.   
To compound the problem, LDAP will return results based not only on 
the starting character of the address but if that character appears at 
all in the address so typing an 'a' to start an address will return 
everything from alansmith to zumberaya.

I would suggest holding back on any searches for address completion 
until the user has typed in at least 3 characters.