To enable alarms in Horde Groupware Webmail you must add the following to your crontab:
# Horde Alarms */5 * * * * /usr/bin/php /var/www/horde/scripts/alarms.php
Depending on your system, the paths above might be different.
You may experience the following error message when the script is run by cron:
Allowed memory size of 8388608 bytes exhausted (tried to allocate 147 bytes)
To resolve this, edit the file /etc/php4/cli/php.ini. Depending on your system it might be located somewere else on your particular system. Change the memory limit to 128 MB by changing the memory_limit parameter:
memory_limit = 128M
The above problem has occured with Horde Groupware Webmail version 1.2.3 but might occur in other versions as well.