I have web calendar (installed via one-click) sending out reminders okay. Check through the admin panel that you have turned email sending on.
My crontab setting is:-
1,11,21,31,41,51 * * * * /usr/local/bin/php /home/username/calendar.example.com/tools/send_reminders.php >/dev/null 2>&1
There is a space after php if that does not show clearly.
Later.
This is from the FAQ page. Apologies if you have read it before. Ignore the php.ini bit unless you have your own PHP version 4.x installed. (Webcalendar may not work under PHP 5)
I am not receiving any email messages from WebCalendar.
WebCalendar sends two types of email messages: Notifications* and Reminders*. Check the following if you are not receiving any email:
1. You have defined a valid SMTP server in your PHP configuration file php.ini. (The setting is "SMTP" in the "mail_function" section.)
2. In WebCalendar's System Settings, you have set the "Email Enabled" setting to "Yes".
3. In WebCalendar's System Settings, make sure you have the "Default sender address" to something.
Note: Some mail system will reject mail that has a "From" address that is a different domain from the originating SMTP server. So, if your SMTP server is smtp.mydomain.com and your "Default sender address" is calendar@someotherdomain.com, some mail systems may bounce the mail back.
4. For a Notification, make sure you have the type of Notification set to "Yes" in the user's Preferences.
5. For a Reminder:
* Make sure you have "Event reminders" set to "Yes" in the user's Preferences.
* Make sure you have setup a cron job to periodically run the send_reminders.php script.