[Bug] EmlParser has incomplete header

[mgabriel-silva]

Describe the bug
The header show by EmlParser is incomplete.
There's only the last 'Received' information

Expected behavior
The header should have multiple 'Received' atributes for all the points it has passed.

Possible solutions
Problably the 'Received's are being lost because of the use of json (or dict), as it can have only one attribute of the same name.
Extracting the entire header as a string should solve the problem (if possible).