These common practices put your data at risk of Man-in-the-Middle (MitM) attacks. Cyber thieves can all so alter the data across the communication path to deliver a malicious payload or modify the contents of files. Knowing who has a given set of information and when they possessed it can provide the paper trail necessary to track down leaks or modifications to documents intended or otherwise. Using E-mail or Instant Messaging to share data puts your data in danger of MitM attacks.”]
Source: https://informationsecuritybuzz.com/articles/importance-data-integrity/