Use Postmark + requests

postmark.py

import os
from base64 import b64encode

import requests
from django.conf import settings
from django.template.loader import render_to_string
import magic


try:
    token = settings.POSTMARK_APIKEY
except AttributeError:
    token = 'POSTMARK_API_TEST'


def sendmail(sender, recipient, subject, template_name, context, attachements=None):
    data = {
        "From": sender,
        "To": recipient,
        "Subject": subject,
        "HtmlBody": render_to_string(template_name + '.html'),
        "TextBody": render_to_string(template_name + '.txt'),
    }

    if attachements:
        data["attachments"] = []
        for file_obj in attachements:
            if isinstance(file_obj, str):  # Is this a path to a file?
                with open(file_obj, 'rb') as input_file:
                    name = file_obj
                    content_type = magic.from_file(file_obj)
                    payload = b64encode(input_file.read())
            else:
                payload = b64encode(file_obj.read())
                try:
                    name = file_obj.file.name  # Django file
                except AttributeError:
                    name = file_obj.name  # Regular file?
                    file_obj.seek(0)
                    content_type = magic.from_buffer(file_obj.read(1024))
                else:
                    content_type = magic.from_file(name)

            data["attachments"].append({
                "Name": os.path.basename(name),
                "Content": payload,
                "ContentType": content_type
            })