or download this
#!/usr/bin/perl
# Script to parse logfile as specified in PerlMonks node 619685
...
mail2-in - postfix/smtpd: warning: 84.9.96.201: address not listed for
+ hostname mail.intechcentre.com
mail2-in - postfix/smtpd: warning: 190.8.87.73: hostname din-190-8-87-
+73.manquehue.net verification failed: hostname nor servname provided,
+ or not known
mail2-in - postfix/smtpd: warning: 190.8.87.73: hostname din-190-8-87-
+73.manquehue.net verification failed: hostname nor servname provided,
+ or not known