How to send email to multiple recipients using python smtplib?

After much searching I couldn't find out how to use smtplib.sendmail to send to multiple recipients. The problem was every time the mail would be sent the mail headers would appear to contain multiple addresses, but in fact only the first recipient would receive the email.

The problem seems to be that the email.Message module expects something different than the smtplib.sendmail() function.

In short, to send to multiple recipients you should set the header to be a string of comma delimited email addresses. The sendmail() parameter to_addrs however should be a list of email addresses.

from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText
import smtplib

msg = MIMEMultipart()
msg["Subject"] = "Example"
msg["From"] = "[email protected]"
msg["To"] = "[email protected],[email protected],[email protected]"
msg["Cc"] = "[email protected],[email protected]"
body = MIMEText("example email body")
msg.attach(body)
smtp = smtplib.SMTP("mailhost.example.com", 25)
smtp.sendmail(msg["From"], msg["To"].split(",") + msg["Cc"].split(","), msg.as_string())
smtp.quit()

Solution 1:

This really works, I spent a lot of time trying multiple variants.

import smtplib
from email.mime.text import MIMEText

s = smtplib.SMTP('smtp.uk.xensource.com')
s.set_debuglevel(1)
msg = MIMEText("""body""")
sender = '[email protected]'
recipients = ['[email protected]', '[email protected]']
msg['Subject'] = "subject line"
msg['From'] = sender
msg['To'] = ", ".join(recipients)
s.sendmail(sender, recipients, msg.as_string())

Solution 2:

The msg['To'] needs to be a string:

msg['To'] = "[email protected], [email protected], [email protected]"

While the recipients in sendmail(sender, recipients, message) needs to be a list:

sendmail("[email protected]", ["[email protected]", "[email protected]", "[email protected]"], "Howdy")

Solution 3:

You need to understand the difference between the visible address of an email, and the delivery.

msg["To"] is essentially what is printed on the letter. It doesn't actually have any effect. Except that your email client, just like the regular post officer, will assume that this is who you want to send the email to.

The actual delivery however can work quite different. So you can drop the email (or a copy) into the post box of someone completely different.

There are various reasons for this. For example forwarding. The To: header field doesn't change on forwarding, however the email is dropped into a different mailbox.

The smtp.sendmail command now takes care of the actual delivery. email.Message is the contents of the letter only, not the delivery.

In low-level SMTP, you need to give the receipients one-by-one, which is why a list of adresses (not including names!) is the sensible API.

For the header, it can also contain for example the name, e.g. To: First Last <[email protected]>, Other User <[email protected]>. Your code example therefore is not recommended, as it will fail delivering this mail, since just by splitting it on , you still not not have the valid adresses!

Solution 4:

It works for me.

import smtplib
from email.mime.text import MIMEText

s = smtplib.SMTP('smtp.uk.xensource.com')
s.set_debuglevel(1)
msg = MIMEText("""body""")
sender = '[email protected]'
recipients = '[email protected],[email protected]'
msg['Subject'] = "subject line"
msg['From'] = sender
msg['To'] = recipients
s.sendmail(sender, recipients.split(','), msg.as_string())

Solution 5:

The solution below worked for me. It successfully sends an email to multiple recipients, including "CC" and "BCC."

toaddr = ['mailid_1','mailid_2']
cc = ['mailid_3','mailid_4']
bcc = ['mailid_5','mailid_6']
subject = 'Email from Python Code'
fromaddr = 'sender_mailid'
message = "\n  !! Hello... !!"

msg['From'] = fromaddr
msg['To'] = ', '.join(toaddr)
msg['Cc'] = ', '.join(cc)
msg['Bcc'] = ', '.join(bcc)
msg['Subject'] = subject

s.sendmail(fromaddr, (toaddr+cc+bcc) , message)