General Email Security Settings
In Email Security > General, you can set up the following:
Service identity username: Select the service identity user from the dropdown list. This is a mandatory step if you want users on the domain to be able to send emails for encryption, even when they have not completed their account setup or if they have not yet been added as an identity. See Editing Identities to learn how to set up a user as a service identity.
Note
If your spam filter has display name spoofing detection enabled, then it is recommended that you do not use a user alias for the service identity email address. This is because it may result in a display name false positive. It is recommended that a noreply, support, or admin alias be used, because these are unlikely to trigger a display name false positive.
Retention policy (in days): Set the number of days for which the email will be retained. The default is 60 days.
Maximum file size allowed (in MB): Set the maximum file size that can be attached in the email.