Sendmail very slow - /etc/hosts configuration

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?

Solution 1:

Got the answer at superuser.com https://superuser.com/a/626219/242163:

Sendmail requires that the result of "hostname" be a fully qualified domain name to start cleanly.

Set the hostname to something like piotr-probook.localdomain and update /etc/hosts.

/etc/hosts

127.0.0.1   piotr-probook.localdomain piotr-probook localdev localhost

Solution 2:

The above answer didn't work for me. So I am posting here what I have done to make it work.

Installed send mail through terminal

apt-get install sendmail

then opened the hosts file

# edited from: sudo gedit etc/hosts
sudo gedit /etc/hosts

replaced the the line

127.0.0.1 localhost

with

127.0.0.1 localhost localhost.localdomain mydomainname

To get the domain name please type

hostname

in terminal and run.

restart apache

sudo service apache2 restart