==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.6 MYSQL edition.
- Linux/BSD distribution name and version: FreeBSD 11
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MYSQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- Related log if you're reporting an issue: crontab
====

After fresh install I had to manually add the sogo.cron because:

root@mx:~ # crontab -l -u sogod
crontab: no crontab for sogod

You might wanna check it, sogo_cron_setup function seems to do nothing