You can share with groups, regular (registered) users, and temp users. An email address is required for temp users.
Temp users can expire based on policy such as a predetermined window, an interval of inactivity, or a download quota. If configured, your administrator can enable you to re-activate inactive TempUsers. For details, see View/Apply Share Settings.
For purposes of secure folder sharing, a single notification email address can not be configured for more than one MOVEit Transfer user account. If you try to share a folder and an email address 'collision' is detected, the WebUI asks you to use an alternate email address or username before it can proceed to share the folder.