Postfix itself does not create a mail logging, but it since it is running as a service its activities are being monitored (and logged) by journalctl.
Thus it is possible to generate a mail.log manualy.
To list the activities of postfix since its last reboot just just enter at a bash the following command:

journalctl -f -u postfix.service (followed by 'Enter')

If however a list of activities for a predefined period is wanted enter the following command:

journalctl -f --since '7 days ago' -u postfix.service >> mail.log (followed by 'Enter')

This will create a file called 'mail.log' that can be opened/searched with a text editor.