as title, I have tried and failed... This is a piece of code I found in another thread and it works for only one recipient. Thanks in Advance.
OutApp <- COMCreate("Outlook.Application")
outMail = OutApp$CreateItem(0)
outMail[["To"]] = "xxx@xxx"
outMail[["subject"]] = "xx"
outMail[["body"]] = ""
outMail$Send()