The default reminder status for calendars in eM Client is set to "No Reminder." But you can adjust the default reminder time for all calendars or even for each calendar individually.

Fo Global reminder settings go to Menu > Tools > Settings > Calendar. Scroll down to Defaults and click 'Set' for default reminder. Here you can choose the time for your default reminder and if you want to assign it to all calendars or select manually which folders to assign the default to.

You can also change the Reminder on an individual calendar in the Calendar section of eM Client. Just right-click the calendar, select Properties and change the Default reminder under the General tab.