funga@funga:~$ ss -lpn | grep :25
tcp    LISTEN     0      0              127.0.0.1:25                    *:*
tcp    LISTEN     0      0              127.0.0.1:25                    *:*
funga@funga:~$ ps aux | grep postfix
funga    23696  0.0  0.1  12084   844 pts/0    S+   11:28   0:00 grep --color=auto postfix
funga@funga:~$ sudo service postfix stop
 * Stopping Postfix Mail Transport Agent postfix                                                                                       [ OK ]
funga@funga:~$ sudo service postfix start
 * Starting Postfix Mail Transport Agent postfix                                                                                       [ OK ]
funga@funga:~$ ps aux | grep postfix
funga    23828  0.0  0.1  12084   848 pts/0    S+   11:28   0:00 grep --color=auto postfix
funga@funga:~$ ps aux | grep sendmail
funga    23833  0.0  0.1  12084   836 pts/0    R+   11:28   0:00 grep --color=auto sendmail
root     31143  0.0  0.0  88104   516 ?        Ss   Mar27   0:07 sendmail: MTA: accepting connections
funga@funga:~$ sudo apt-get autoremove sendmail
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'sendmail' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 147 not upgraded.