This should help you get Sendmail installed with basic configuration on Ubuntu.
- If sendmail isn't installed, install it: 
sudo apt-get install sendmail - Configure 
/etc/hostsfile:nano /etc/hosts - Make sure the line looks like this: 
127.0.0.1 localhost yourhostname - Run Sendmail's config and answer 'Y' to everything: 
sudo sendmailconfig - Restart apache 
sudo service apache2 restart 
after doing your steps, i get this
[Mon Feb 24 09:50:24.782752 2020] [mpm_prefork:notice] [pid 11060] AH00169: caught SIGTERM, shutting down
[Mon Feb 24 09:52:08.852440 2020] [mpm_prefork:notice] [pid 1128] AH00163: Apache/2.4.29 (Ubuntu) configured -- resuming normal operations
[Mon Feb 24 09:52:09.024401 2020] [core:notice] [pid 1128] AH00094: Command line: '/usr/sbin/apache2'
what do i do?