[Dovecot] md5_verify(...): Not a valid MD5-CRYPT or PLAIN-MD5 password

[BaQs]

'afternoon list! 

I use mysql as userdb, which contains two type of
password schemes: DES and MD5-CRYPT. 

I read there :


http://wiki.dovecot.org/Authentication/PasswordSchemes 

that both are
supported by dovecot. 

Unfortunately, dovecot keeps saying: Not a valid
MD5-CRYPT or PLAIN-MD5 password when looking for a user with DES encrypted
password. 

Is dovecot able to recognize password scheme, or do I have to
do something else ? 

I can't add {DES} to DES passwords, as this database
is used with many other softwares. 

Thanks a lot for your help 

Pierre