Encryption of an email message is the process of protecting your confidential data from being read by onlookers trying to get hold of your email message. The sensitive information might be related to social society numbers, passwords, login credentials, and bank account numbers. Send a secure email in Outlook subject line is essential because it protects your sensitive information from a data breach. The hacker cannot read your secured email even if they get to access the email you sent. Only the recipient has access to read the email message. They have to decrypt the email message using the corresponding key.