Make sure that your Identity Vault users have the Internet EMail Address attribute populated.
If you are using e-mail notifications for Password Synchronization, make sure that the Password Synchronization driver policies contain the password for the SMTP server. See Providing SMTP Authentication Information in Driver Policies.
If you are concerned that some users might not have the e-mail address populated, or if you want an e-mail record of all failure notifications, consider choosing a password administrator account that all e-mail notifications are sent to, in addition to the user.
This e-mail address should be in the To field of the Identity Manager script policy. For more information, see Sending E-Mail Notifications to the Administrator.
If eDirectory and Identity Manager are on a UNIX server, the server must hold a replica of the e-mail template objects.
These objects are located in the Security container, at the root. This means that the server needs a replica of the root partition.