Question

Please forgive me up front. When I’ve tried to research this question I end up looking at code that I simply can’t comprehend. I have about 3 hours of experience with Python and am probably attempting more than I can handle.

The problem is simple. I can successfully call Python from R (my analysis software) to send an e-mail. Adding the message, subject, to, and from fields I can do. I’d like to be able to send an attachment. Life would be great if I could send just one attachment.

The code I have thus far is

import smtplib
import os
from email.MIMEMultipart import MIMEMultipart
from email.MIMEBase import MIMEBase
from email.MIMEText import MIMEText
from email.Utils import COMMASPACE, formatdate
from email import Encoders
import email.utils

fromaddr = '[e-mail]'
toaddrs  = '[e-mail]'
msg = MIMEMultipart(MIMEText('This is the body of the e-mail'))
msg['From'] = email.utils.formataddr(('Benjamin Nutter', fromaddr))
msg['To'] = email.utils.formataddr(('Benjamin Nutter', toaddrs))
msg['Subject'] = 'Simple test message'
f = 'filename.pdf'
part=MIMEBase('application', 'octet-stream')
part.set_payload(open(f, 'rb').read())
Encoders.encode_base64(part)
part.add_header('Content-Disposition', 'attachment; filename=\"%s\"' %    os.path.basename(f))
msg.attach(part)

"username = 'user'
"password = 'pw'

server = smtplib.SMTP('smtp.gmail.com:587')
server.ehlo()
server.starttls()
server.ehlo()
server.login(username,password)
server.sendmail(fromaddr, toaddrs, msg.as_string())
server.quit()

When I run this code, I get the message
string payload expected: [type ‘list’] (but with < not [)

I’m at my limit for self-learning today. I’m hoping this is an obvious fix to someone more experienced than myself.

I hope you’re all having a great day.

Answer 1

I know it’s bad form to answer my own question, but it started working miraculously with no changes. What a way to make my first impression, right?

Anyway, I wrapped it into an R function. This will send from gmail, but I haven’t tried sending it from other accounts yet. I’m most interested in sending from Outlook, since I’d be using this to send analysis reports from within my scripts. When I entered my employer’s SMTP server, it gave the error “SMTP AUTH extension not supported by server.” I suspect I’ll have to work this out with my tech support guys.

This will probably only work on Windows, thanks to the winDialog() functions. But it’s a good start.

send.email <- function(to, from, subject, 
  message, attachment=NULL,
  username, password,
  server="smtp.gmail.com:587",
  confirmBeforeSend=TRUE){
  # to: a list object of length 1.  Using list("Recipient" = "[e-mail]") will send the message to the address but 
  #     the name will appear instead of the address.
  # from: a list object of length 1.  Same behavior as 'to'
  # subject: Character(1) giving the subject line.
  # message: Character(1) giving the body of the message
  # attachment: Character(1) giving the location of the attachment
  # username: character(1) giving the username.  If missing and you are using Windows, R will prompt you for the username.
  # password: character(1) giving the password.  If missing and you are using Windows, R will prompt you for the password.
  # server: character(1) giving the smtp server.
  # confirmBeforeSend: Logical.  If True, a dialog box appears seeking confirmation before sending the e-mail.  This is to 
  #                    prevent me to send multiple updates to a collaborator while I am working interactively.  

  if (!is.list(to) | !is.list(from)) stop("'to' and 'from' must be lists")
  if (length(from) > 1) stop("'from' must have length 1")
  if (length(to) > 1) stop("'send.email' currently only supports one recipient e-mail address")
  if (length(attachment) > 1) stop("'send.email' can currently send only one attachment")
  if (length(message) > 1){ 
    stop("'message' must be of length 1")
    message <- paste(message, collapse="\\n\\n")
  }

  if (is.null(names(to))) names(to) <- to
  if (is.null(names(from))) names(from) <- from
  if (!is.null(attachment)) if (!file.exists(attachment)) stop(paste("'", attachment, "' does not exist!", sep=""))

  if (missing(username)) username <- winDialogString("Please enter your e-mail username", "")
  if (missing(password)) password <- winDialogString("Please enter your e-mail password", "")

  require(rJython)
  rJython <- rJython()

  rJython$exec("import smtplib")
  rJython$exec("import os")
  rJython$exec("from email.MIMEMultipart import MIMEMultipart")
  rJython$exec("from email.MIMEBase import MIMEBase")
  rJython$exec("from email.MIMEText import MIMEText")
  rJython$exec("from email.Utils import COMMASPACE, formatdate")
  rJython$exec("from email import Encoders")
  rJython$exec("import email.utils")

  mail<-c(
  #Email settings
  paste("fromaddr = '", from, "'", sep=""),
  paste("toaddrs  = '", to, "'", sep=""),
  "msg = MIMEMultipart()",
  paste("msg.attach(MIMEText('", message, "'))", sep=""),
  paste("msg['From'] = email.utils.formataddr(('", names(from), "', fromaddr))", sep=""),
  paste("msg['To'] = email.utils.formataddr(('", names(to), "', toaddrs))", sep=""), 
  paste("msg['Subject'] = '", subject, "'", sep=""))

  if (!is.null(attachment)){
    mail <- c(mail,
      paste("f = '", attachment, "'", sep=""),
     "part=MIMEBase('application', 'octet-stream')",
     "part.set_payload(open(f, 'rb').read())",
     "Encoders.encode_base64(part)",
     "part.add_header('Content-Disposition', 'attachment; filename=\"%s\"' % os.path.basename(f))",
     "msg.attach(part)")
  }

#SMTP server credentials
  mail <- c(mail, 
    paste("username = '", username, "'", sep=""),
    paste("password = '", password, "'", sep=""),

#Set SMTP server and send email, e.g., google mail SMTP server
    paste("server = smtplib.SMTP('", server, "')", sep=""),
    "server.ehlo()",
    "server.starttls()",
    "server.ehlo()",
    "server.login(username,password)",
    "server.sendmail(fromaddr, toaddrs, msg.as_string())",
    "server.quit()")

  message.details <- 
    paste("To:               ", names(to), " (", unlist(to), ")", "\n",
          "From:             ", names(from), " (", unlist(from), ")", "\n",
          "Using server:     ", server, "\n",
          "Subject:          ", subject, "\n",
          "With Attachments: ", attachment, "\n",
          "And the message:\n", message, "\n", sep="")

  if (confirmBeforeSend) 
   SEND <- winDialog("yesnocancel", paste("Are you sure you want to send this e-mail to ", unlist(to), "?", sep=""))
   else SEND <- "YES"

  if (SEND %in% "YES"){ 
    jython.exec(rJython,mail)
    cat(message.details)
  }
  else cat("E-mail Delivery was Canceled by the User")
}