courier imapd login failed

[YaP]

I've a problem sending email with imp. The authentication works when i login 
to read emails but when i try to send an email the compose page refresh and i 
got this in maillog:

Mar 29 00:10:05 roberto imapd: LOGIN, user=yap, ip=[::ffff:127.0.0.1]
Mar 29 00:10:05 roberto imapd: LOGOUT, user=yap, ip=[::ffff:127.0.0.1], 
headers=0, body=0
Mar 29 00:10:05 roberto imapd: Connection, ip=[::ffff:127.0.0.1]
Mar 29 00:10:06 roberto imapd: LOGIN FAILED, ip=[::ffff:127.0.0.1]
Mar 29 00:10:06 roberto imapd: LOGOUT, ip=[::ffff:127.0.0.1]

Can you help me solving this problem?

I use:
php 4.0.4pl1
horde 1.2.4
imp 2.2.4
courier-imapd 1.3.5 + authvckpw

Thanks

Andrea Parrella