Here you can see, how to change MTA qmail to any other you can set as simple sendmail or postfix, exim or qmail.
`[[email protected]~]#ll /etc/alternatives/mta`
lrwxrwxrwx 1 root root 23 Aug 31 03:39 /etc/alternatives/mta -> /var/qmail/bin/sendmail
[[email protected] ~]# alternatives –config mta
There are 4 programs which provide ‘mta’.
*+ 1 /var/qmail/bin/sendmail
Enter to keep the current selection[+], or type selection number: 2
Please comment if any issues.