How to write an email to staff that everyone should speak in English during office hours and client's place?

How to write an email to staff that everyone should speak in English during office hours and client's place?

Dear Srini
Check whether you can frame like this.
Dear ______
Good morning.
Greetings From HR department!!
All the employees are requested to inculcate English as a part of their workplace culture. As business is growing and people are networking with clients English is becoming essential. So as a part of new culture all the employees are requested to speak in English during the office hours and also in Client place. The management is also planning to set English skills as part of KRA.
Regards
_____

Dear Mr.Srini,
We need to first ensure that the HR Manual any mention has been made about the Official Language. Because this change is also a policy issue, it has to be made properly. Until the policy change is made, informally keep encouraging the staff to converse in English. Everything comes by practice. Once the policy change is effected, make it a rule.

I wonder, if he is really an HR professional! He seems to be seeking help in fulfilling requirement of his classroom exercise of his management school.