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

'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