How to specify remote file attachment for SMTP mail in Python - python-3.x

Question

How can the remote attachment file be specified to be included in SMTP mail? Attachement file is located on different server (own username/password access)
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email import encoders
mail_content = """ This is body content """
sender_addr = "sender_addr#server.com"
sender_pass = "apassword"
receiver_addr = "receiver_addr#server.com"
# Create MIME header
msg = MIMEMultipart()
msg['From'] = sender_addr
msg['To'] = receiver_addr
msg['Subject'] = 'A test mail subject sent by Python'
msg.attach(MIMEText(mail_content, 'plain'))
fname = "doc_1.pdf"
attach_file = open(fname, 'rb') # **<- How can I specify the remote path here?**
payload = MIMEBase('application', 'octet-stream')
# Attach an attachment to payload
payload.set_payload((attach_file).read())
encoders.encode_base64(payload)
# Add payload header with filename
payload.add_header('Content-Disposition', 'attachment', filename=fname)
msg.attach(payload)
# Create SMTP client
client = smtplib.SMTP('smtp.gmail.com', 587)
client.starttls()
client.login(sender_addr, sender_pass)
text = msg.as_string()
client.sendmail(sender_addr, receiver_addr, text)
client.quit()
print('Mail sent!')

Answer 1

https://www.rfc-editor.org/rfc/rfc2110#section-4.1 explains the Content-Location: header.
Assuming the content you want to link to is in the variable attach_uri, something like
# Create MIME header
msg = MIMEMultipart()
msg['From'] = sender_addr
msg['To'] = receiver_addr
msg['Subject'] = 'A test mail subject sent by Python'
msg.attach(MIMEText(mail_content, 'plain'))
payload = MIMEBase('application', 'octet-stream')
payload.add_header('Content-Location', attach_uri)
msg.attach(payload)
If you are asking how to retrieve stuff from a remote location and include it in an email, that's a pretty broad topic; but assuming you have the content on an HTTP server, try something like
import requests
r = requests.get(attachment_uri)
payload.set_payload(r.content)
before you msg.attach(payload).
With this, there should be no need to set the Content-Location: to the original URI any longer (why would the user care where it came from? And you don't want to reveal the password etc).