Deloitte internal email systems breach, maybe its time to reassess how we craft our emails. Getting access to a messaging server usually provides a wealth of information which can be used for further attacks including spear phishing. Always review an email as though it might be read by someone other than the intended recipient. When you Bcc someone on a confidential email, dont expect them to know not to forward it to someone else unless you tell them in advance. If you must say something critical about someone it is probably better to pick up the phone and call the intended email recipient and explain it to them.”]
Source: https://www.csoonline.com/article/3227796/how-is-your-email-security-hygiene.html