I am from china.now, i want to write an email to some stranger purchase managers. how to write the email? thank u.

1, Lots of people say, Each company purchase manager received many many promotion letters. so if your email subject is not attraction.it may be unread and is deleted by the purchase manager. so could u give me some suggestions if i promote medical disposable products(shoes cover,gown,face mask). how to write an attraction subject?thank u