[Dovecot] IMAP proxying for ALL users to internal mail server

[Vitaliy Vladimirovich]

 Hi!  
   
   How must I adjust Dovecot for proxying all users from the Internet to the internal Exchange Mail Server?  
  
 This is my config files (most important):  
  
   dovecot.conf  
   
    protocol imap {  
    #listen = *:10143  
    ssl_listen = 194.0.148.10:993  
   
   auth default {  
           mechanisms = plain login  
        
           passdb passwd-file {  
           args = /usr/local/etc/dovecot-%Ls.conf  
                                              }  
 }  
   
  dovecot-imap.conf  
  testmail1 at example.org::0:0::::proxy host=10.0.10.3 port=143 nopassword  
   
 With this configurations all works fine, but if I trying change dovecot-imap.conf as below  
  
 %n@%d::0:0::::proxy host=10.0.10.3 port=143 nopassword  
  
I get an error:  
  
Oct  2 15:10:58 relay dovecot: auth(default): client in: AUTH   1       PLAIN   service=imap    secured lip=199.10.149.10     rip=199.10.149.3  lport=993       rport=28316     resp=<hidden>  
Oct  2 15:10:58 relay dovecot: auth(default): passwd-file(testmail1 at example.org,199.10.149.3): lookup: user=testmail1 at example.org file=/usr/local/etc/dovecot-imap.conf  
Oct  2 15:10:58 relay dovecot: auth(default): passwd-file(testmail1 at example.org,199.10.149.3): unknown user  
Oct  2 15:10:59 relay dovecot: auth(default): new auth connection: pid=62532  
Oct  2 15:11:00 relay dovecot: auth(default): client out: FAIL  1       user=testmail1 at example.org  
  
  
Any ideas??