unexpected unindent error when sending mail from .txt document

Question

I am writing a program to send an email (from message.txt) to email addresses which are stored in email.txt. Sending an empty email works flawlessly, but if I use the txt or the message it throws the syntax error "unexpected unindent" on the very last line of code. Why is that and what can I do to solve it?

EDIT: I have read through other people's problems getting the same error, but their error's origin is very different to mine, hence I cannot conclude anything from their solutions...

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

def send_email(user, pwd, recipients, subject):
    try:        
        with open('message.txt') as fp:
            # Create a text/plain message
            msg = MIMEText(fp.read())
        recipients = []
        with open('emails.txt') as f:
            for line in f:
                if len(line.strip()) > 0:
                    recipients.append(line.strip())
        #container
        msg = MIMEMultipart('alternative')        
        msg['Subject'] = 'Your reminder'
        msg['From'] = 'example@gmail.com'
        msg['To'] = ','.join(recipients)
        msg.attach(msg)
        server = smtplib.SMTP("smtp.gmail.com", 587)
        server.starttls()
        server.login(user, pwd)
        server.sendmail(user, recipients, msg.as_string())
        server.close()
        print("Sent the email!")
send_email("example@gmail.com", "password", "Subject",     "A reminder")

Answer 1

You've used the variable name msg as both the MIMEText message attachment and the MIMEMultipart message container. In the code below, I've changed the name for the MIMEText variable to be strMessage.

The unexpected unindent occurs because the try block isn't complete. Either add something to the try block to complete the compound statement:

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

def send_email(user, pwd, recipients, subject):
    try:        
        with open('message.txt') as fp:
            # Create a text/plain message
            strMessage = MIMEText(fp.read())
        recipients = []
        with open('emails.txt') as f:
            for line in f:
                if len(line.strip()) > 0:
                    recipients.append(line.strip())
        #container
        msg = MIMEMultipart('alternative')        
        msg['Subject'] = 'Your reminder'
        msg['From'] = 'example@gmail.com'
        msg['To'] = ','.join(recipients)
        msg.attach(strMessage)
        server = smtplib.SMTP("smtp.gmail.com", 587)
        server.starttls()
        server.login(user, pwd)
        server.sendmail(user, recipients, strMessage.as_string())
        server.close()
        print("Sent the email!")
    finally:
        pass
send_email("example@gmail.com", "password", "Subject",     "A reminder")

Or omit the try entirely:

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

def send_email(user, pwd, recipients, subject):
            with open('message.txt') as fp:
                # Create a text/plain message
                strMessage = MIMEText(fp.read())
            recipients = []
            with open('emails.txt') as f:
                for line in f:
                    if len(line.strip()) > 0:
                        recipients.append(line.strip())
            #container
            msg = MIMEMultipart('alternative')
            msg['Subject'] = 'Your reminder'
            msg['From'] = 'example@gmail.com'
            msg['To'] = ','.join(recipients)
            msg.attach(strMessage)
            server = smtplib.SMTP("smtp.gmail.com", 587)
            server.starttls()
            server.login(user, pwd)
            server.sendmail(user, recipients, strMessage.as_string())
            server.close()
            print("Sent the email!")
send_email("example@gmail.com", "password", "Subject",     "A reminder")