Some email clients allow users to export email messages (.eml) as JPEG pictures (.jpg, .jpeg), which can also be achieved using several online conversion services like ZAMZAR. The result of eml to jpg conversion or export will be a simple bitmap image that contains the text from the email in it.
If the picture is just an attachment to the message, you have to just to save it as separate file, no need to convert eml to jpg.
Updated: September 22, 2022