It takes ~15 seconds to send single e-mail using sendmail.
/var/log/mail.log:
Jul 31 09:52:42 piotr-probook sendmail[2912]: My unqualified host name (piotr-probook) unknown; sleeping for retry
/etc/hostname:
piotr-probook
/etc/hosts:
127.0.0.1 piotr-probook localdev localhost
192.168.1.1 router
/etc/mail/sendmail.cf:
# hosts file (normally /etc/hosts)
O HostsFile=/etc/hosts
Obviously I can ping piotr-probook host and HTTP server popups in browser when i type url http://piotr-probook
What am I doing wrong? How to fix the problem?