As a Admin Executive, to whom you report to? Sit with your reporting authority and discuss about your roles, responsibility and deliverable. This will bring clarity about your job.
Secondly, about e-mail etiquette. Lot of material is available on the internet. You could have referred it. More than email etiquette, you may refer ebooks on how to write the business letters. There are free downloadable books available on the internet. Read a letter every day and see the change in yourself.