How will the CreatedBy & ModifiedBy fields get populated incase we allow external users to send emails to a sharepoint list

Question

I am working on SharePoint server 2013, and i have added an Announcement list. then i configure the announcement list to receive in-coming emails from external users (users not defined inside our active directory). But my question is how will the CreatedBy & ModifiedBy fields get populated for an item, when an email is received inside the list? as the external user will not be registered inside the Active Directory ? will these be equal to the external user email address for example ?

Answer 1

They will be populated with "System Account".

Answer 2

If users are required to authenticate then it would be the "username" probably email in case of sharepoint online or if they are not required to authenticate then it would be "Guest Contributor" in the modified field.

more detail here and here