If you have  <security/pam_appl.h>  header in your system,
you have already compiled the PAM-based SHADOW support in.
To complete it, you will need following file:


------- /etc/pam.d/smtpauth-login -----------
#%PAM-1.0
auth       required     /lib/security/pam_pwdb.so shadow
auth       required     /lib/security/pam_nologin.so
account    required     /lib/security/pam_pwdb.so
---------------------------------------------
