Python – Sending mail via sendmail from python

emailpythonsendmail

If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?

Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?

I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.

As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself — so just dumping a string to popen('/usr/bin/sendmail', 'w') is a little closer to the metal than I'd like.

If the answer is 'go write a library,' so be it 😉

Best Solution

Header injection isn't a factor in how you send the mail, it's a factor in how you construct the mail. Check the email package, construct the mail with that, serialise it, and send it to /usr/sbin/sendmail using the subprocess module:

import sys
from email.mime.text import MIMEText
from subprocess import Popen, PIPE


msg = MIMEText("Here is the body of my message")
msg["From"] = "me@example.com"
msg["To"] = "you@example.com"
msg["Subject"] = "This is the subject."
p = Popen(["/usr/sbin/sendmail", "-t", "-oi"], stdin=PIPE)
# Both Python 2.X and 3.X
p.communicate(msg.as_bytes() if sys.version_info >= (3,0) else msg.as_string()) 

# Python 2.X
p.communicate(msg.as_string())

# Python 3.X
p.communicate(msg.as_bytes())