Email route (or routing) is the route that a email message has taken from server to server before landing in a mailbox.
Received is a message header which indicates when and how a server handled the message.
The show the path that a message takes from the message sender to the final recipient.
spammers may also add additional Received headers, before they send the message, to make it look like the message originated som
The route is defined via the Received header that is happened by every server when it receives an message. The list of all Received header forms a route.
They are read in reverse order:
Received: by 172.16.84.104 with SMTP id ax2nko4a19iuvwy9mhdlr7d5wxu6sln7jocea;
Thu, 4 Feb 2021 18:00:11 GMT
You can get it formatted with the Message header toolbox.