It is a function that extends the sendmailR :: sendmail.
It is to be able to and can set the "content type" to "header" and send it to multiple destinations.
Usage
sendmailEx(from, to, subject, msg, headers = list(),
control = list(),is.debug=F)
Arguments
from
From whom the mail message is (RFC2822 style
address).
to
Recipient of the message (valid RFC2822 style
address).
subject
Subject line of message.
msg
Body text of message or a list containing
sendmailR::mime_part objects.
headers
Any other headers to include.
control
List of SMTP server settings. Valid values
are the possible options for sendmailR::sendmail_options.
is.debug
debug flag. If TRUE, not send mail.
Examples
## Not run:
from <- sprintf("<sendmailR@\%s>", Sys.info()[4])
to <- "<olafm@datensplitter.net>"
subject <- "Hello from R"
body <- list("It works!", mime_part(iris))
sendmail(from, to, subject, body,
control=list(smtpServer="ASPMX.L.GOOGLE.COM"))
## End(Not run)
providing 
.