How to send a properly formatted email using Python and SMTP?

Question

I am trying to send an email using Python script but somehow in the format I am expecting the email to come in my mailbox, it is not coming in that format. Below is my method which is sending an email -

def send_mail(data):
    sender = 'fromuser@host.com'
    receivers = ['touser@host.com']

    message = """From: fromuser@host.com
    To: touser@host.com
    Subject: Send mail from python!!

    """
    body = 'Some Text\n'
    for item in data:
        body = body + '{name} - {res}\n'.format(name=item['name'], res=item['res'])

    message = message + body

    try:
       smtpObj = smtplib.SMTP('corp.host.com' )
       smtpObj.sendmail(sender, receivers, message)
       print "Mail sent"
    except smtplib.SMTPException:
       print "You can't spam. Mail sending failed!"

Here data just have key - value pair.

And I am getting an email like this in my Outlook mailbox -

In the From: section in my outlook, below string is coming as it is which is wrong -

fromuser@host.com To: touser@host.com Subject: Send mail from python!!

And To: , Subject: section is coming as Empty which is also wrong.

And in the body I am seeing everything coming in a single line but I want the result to be shown as -

Some Text

machinA - 0
machineB - 0
machineC - 0

How can I represent my data to be shown like this in my Outlook mailbox?

Answer 1

Since triple quoting preserves all spaces, you were accidentally sending:

From: fromuser@host.com
      To: touser@host.com
      Subject: Send mail from python!!

This invokes header unfolding: indented lines mean that the header is continued. So this really is a badly formatted From header. You need to make sure there are no extraneous spaces. This fixes up your current example:

def send_mail(data):
    sender = 'fromuser@host.com'
    receivers = ['touser@host.com']

    message = """\
From: fromuser@host.com
To: touser@host.com
Subject: Send mail from python!!
"""
    body = '\n\nSome Text\n'
    for item in data:
        body = body + '{name} - {res}\n'.format(name=item['name'], res=item['res'])

    message = message + body

    try:
       smtpObj = smtplib.SMTP('corp.host.com' )
       smtpObj.sendmail(sender, receivers, message)
       print "Mail sent"
    except smtplib.SMTPException:
       print "You can't spam. Mail sending failed!"

However, you shouldn't be manually constructing messages at all. Python includes an assortment of lovely classes in email.message for constructing a message.

import email.message

m = email.message.Message()
m['From'] = "fromuser@host.com"
m['To'] = "touser@host.com"
m['Subject'] = "Send mail from python!!"

m.set_payload("Your text only body");

Now, you can turn your message into a string:

>>> m.as_string()
'To: touser@host.com\nFrom: fromuser@host.com\nSubject: Send mail from python!!\n\nyour text-only body'

I will warn you, properly dealing with email is a very large and complex topic, and if you want to use non-ascii, attachments, etc, there's a bit of a learning curve, and you will need to use all the faculties of the email.message library, which has a lot of documentation you should read and understand.