SapphireIMS processes the emails to records only if the sender’s email addresses are part of SapphireIMS user list. However, SapphireIMS does has a provision to process such emails to records (which are sent by the users who are not present in SapphireIMS) to be created under a common user / submitter.
This can be done by accessing the ‘Project Settings’ from the ‘General Settings’ tab (link)
Search for the setting key name ‘Enter the email to ticket on behalf userId’ and provide the value with an active UserID who also has a submitter role access in the project. Contact Support team so that they can help you with the UserID from the database.