Warning: C_Calendar::loadAllCalendars(): It is not safe to rely on the system’s timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. 

It’s likely that the system timezone isn’t enabled.

Here’s an instruction how to set the timezone in php.ini in cPanel. If you don’t have cPanel, you can always open in any text editor and edit then save.

Always remember to restart web server after edit php.ini.

For the built-in email reminder that sends emails reminders (cron job required). See https://phpeventcalendar.com/docs/event-emailpopup-reminder/

To setup cron job, it is recommended to use cPanel Cron Job tool. See https://kb.iweb.com/hc/en-us/articles/230244168-Setting-up-cron-jobs-with-cPanel-. This tool is always included in host provider that uses cPanel.

When use PHPMailer, you are required set up an SMTP server in order to send out emails. See https://github.com/PHPMailer/PHPMailer