Emailing under Windows using R

Programatically sending an email under Linux is relatively simple. There are several command line clients such as sendmail and mail which are very easy to use. There are also several R packages to help send emails such as {mailr} and {blastula}.
Generally you need access to an SMTP to send messages programatically and this may not be possible in a work setting.
Here’s a simple R function to send an email under Windows. It uses vbs scripting to send an email via the Outlook client itself, without needing server parameters.

#' Send an email with attachments
#'
#' Sends an email to a recipient using vbs scripting.
#' `body` contains the body of the email and `files` contains a list of files
#' to attach.
#'
#' @param to Recipient email address
#' @param subject Subject line
#' @param body Body text
#' @param files List of files to attach
#'
#' @export
lc_send_email <- function(to = NULL, subject = "", body = "", files = list()) {

  if (is.null(to)) return(NULL)

  if (length(files) > 0) {
    v.files <- unlist(sapply(files, function(f) {
      paste0('myAttachments.Add "', normalizePath(f), '", olByValue')
    }))
  } else {
    v.files <- ''
  }

  ## build a vbs script to send an email to user
  v.outlook_commands <- c(
    'Dim olApp',
    'Dim objMailItem',
    'Dim myAttachments',
    'Set olApp = CreateObject("Outlook.Application")',
    'Set objMailItem = olApp.CreateItem(0)',
    'Set myAttachments = objMailItem.Attachments',
    paste0('objMailItem.Subject = "', subject, '"'),
    paste0('objMailItem.To = "', to, '"'),
    paste0('objMailItem.Body = "', body, '"'),
    v.files,
    'objMailItem.Send',
    'Set olApp = Nothing',
    'Set objMailItem = Nothing'
  )

  ## write script to temporary location
  script_file <- tempfile(fileext = '.vbs')
  sink(script_file, append = FALSE)
  cat(v.outlook_commands, sep='\n')
  sink()

  ## execute script
  system_script <- paste0('WScript ', normalizePath(script_file))
  system(system_script)

}