For this example, we'll use '1XSY5g-0001kh-N6' as the email ID but this ID is unique to each email message - yours will be different.
For the email header, from your terminal, perform the following command:
exim -Mvh 1XSY5g-0001kh-N6
It's important to remember 'M' needs to be capitalized, and all 14 characters of the ID, with the hyphens (-) are included.
Here's an example output:
For the email body, the command is similar. Just using a 'b' for body, rather than 'h' from the previous command:
exim -Mvb 1XSY5g-0001kh-N6