OTRS 5.0.12 Refresh time for FetchMail

[avrileica]

HI,

We have OTRS 5.0.12 and we can't change refresh time interval from 10 min (default value) to any other value.

Daemon::SchedulerCronTaskManager::Task###MailAccountFetch

Schedule have value: */10 * * * *

How we can change this, because it don't allow as.