These few days I have been closely watching the disputes between Mr Lee Hsien Loong and his siblings.  I found that as the Prime Minister of Singapore,  Mr Lee always uses his Prime Minister Office email to communicate with his family members,  e. g.  his wife,  his brother and sister.  I don't believe it is proper use of the office email to handle private and personal matters.  

Remember last year in U.S. president election,  lady Clinton lost her post mainly because of her misuse of email system,  i. e.  use personal email to handle her official matters. 

Usually in any company,  there is certain terms to regulate staff's conducts, proper use of emails for office matters is sure part of the terms.  Misuse of email system,  no matter misuse office email system to handle private and personal matters or misuse private email system to handle office matters,  might cause security issue.  

It is obviously that in the States,  people are very sensitive in this,  especially if it relates to politicians, like Clinton Hillary. However,  in Singapore,  PM Lee and his family and even normal singaporean, obviously belong to another type of mortals, i. e.  totally no sense of security and not political sensitive.