How to get line breaks in e-mail sent using Python's smtplib?

Unfortunately for us all, not every type of program or application uses the same standardization that python does.

Looking at your question i notice your header is: "Content-Type: text/html"

Which means you need to use HTML style tags for your new-lines, these are called line-breaks. <br>

Your text should be:

"Dear Student, <br> Please send your report<br> Thank you for your attention"

If you would rather use character type new-lines, you must change the header to read: "Content-Type: text/plain"

You would still have to change the new-line character from a single \n to the double \r\n which is used in email.

Your text would be:

"Dear Student, \r\n Please send your report\r\n Thank you for your attention"

You have your message body declared to have HTML content ("Content-Type: text/html"). The HTML code for line break is <br>. You should either change your content type to text/plain or use the HTML markup for line breaks instead of plain \n as the latter gets ignored when rendering a HTML document.

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As a side note, also have a look at the email package. There are some classes that can simplify the definition of E-Mail messages for you (with examples).

For example you could try (untested):

import smtplib
from email.mime.text import MIMEText

# define content
recipients = ["[email protected]"]
sender = "[email protected]"
subject = "report reminder"
body = """
Dear Student,
Please send your report
Thank you for your attention
"""

# make up message
msg = MIMEText(body)
msg['Subject'] = subject
msg['From'] = sender
msg['To'] = ", ".join(recipients)

# sending
session = smtplib.SMTP('smtp.gmail.com', 587)
session.starttls()
session.login(sender, 'my password')
send_it = session.sendmail(sender, recipients, msg.as_string())
session.quit()

In my case '\r\n' didn't work, but '\r\r\n' did. So my code was:

from email.mime.text import MIMEText
body = 'Dear Student,\r\r\nPlease send your report\r\r\nThank you for your attention'
msg.attach(MIMEText(body, 'plain'))

The message is written in multiple lines and is displayed correctly in Outlook.