Samsung SVMi-4 User Manual page 16

Undelivered Retrieval
When this function is activated, the SVMi-4 / SVM-400 will allow you to recall
any messages you have sent that have not yet been picked up by the recipient.
l From the mailbox main menu press 6 for mailbox administration.
l Press 4 for undelivered messages.
This useful feature will allow you to cancel any messages that have not yet
been picked up by the recipient.
Mailbox Administration – Page 13