A system generated email in System Logs > Emails displays a sys id in the "type" field rather than the actual display value of the type of email, such as send-ready.
This is a normal operation with processing queues that are processed by multiple scheduled jobs. You are seeing the sys_id for the scheduled "sender" jobs for sending the emails. They are temporarily stored in the type field during processing of the email jobs and you normally will only see them if you are checking jobs very quickly or if you are sending out a lot of emails.
To view and verify this information, you can search for the following sys_id's under "System Scheduler >> Scheduled Jobs" and you will see that these sys_ids are the sys_id's for the scheduled job records called "SMTP Sender", "SMTP Sender2", "SMS Sender"..