Each FortiMail platform, including the VM versions, has hard-coded maximum values for various features and functionalities. As such, they may not be practical limits for every situation and are not a promise of performance.
Starting from 5.2.0, a new mechanism (warning limit/soft limit and hard limit) was introduced to the following three settings: number of protected domains, number of domain associations, and number of mailboxes/mail users in server mode. When the warning limit is reached, FortiMail will display a warning message; when the hard limit is reached, FortiMail will not allow you to add more.
Starting from 6.0.0, the warning/soft limit is removed.
To view the maximum values of all FortiMail models, see the FortiMail Maximum Values document.