When an e-mail notification is sent out from CA Service Desk Manager (CA SDM), under some circumstances, if the e-mail cannot be sent, it is saved in the "NX_ROOT\site\mail_undeliverable" folder. Why are some possible causes?
CA Service Desk Manager : All Supported Versions
If an e-mail notification is sent from CA SDM, it will try to relay the email notification to the email server which is configured in Options Manager.
There are two different scenarios which can occur where the email notification is not delivered, but only one will result in a saved version of the email notification being saved in the NX_ROOT\site\mail_undeliverable folder :
In such cases, since CA SDM is unable to relay the email notification to the email server, this will be considered an undelivered email. A message is logged in the STDLOG, and the email is saved the "mail_undeliverable" directory.