Authenticating Email Discovery as Evidence
Many practitioners think that e-mails are like business letters and will be admitted into evidence just as easily. E-mails, however, may be more prone to problems of authenticity and hearsay than traditional written documents. People often write e-mails casually, dashing off comments with an informality they'd never use with a letter. Little care is given to grammar and context. Their signature or even their name may be omitted. Authenticating an e-mail presents issues not faced with a traditional letter with its formal letterhead, paragraph structure and signature block. Additionally, e-mails are arguably more susceptible to after-the-fact alteration.
https://www.lawweb.in/2012/05/authenticating-email-discovery-as.html