Creates a MailItem object in Microsoft Outlook with stuff already filled in

outlook.py

import win32com.client

class AttachmentInfo:
    def __init__(self, file_path, mime_type, attachment_id=None):
        self.file_path = file_path
        self.mime_type = mime_type
        self.id = attachment_id

def draft_html(
    to=(),
    cc=(),
    bcc=(),
    subject="",
    attachments=(),
    body="",
    display=True
):
    draft = win32com.client.gencache.EnsureDispatch(
        "Outlook.Application"
    ).CreateItem(
        win32com.client.constants.olMailItem
    )
    # Add the To, Cc, and Bcc fields.
    for recipient in to:
        draft.Recipients.Add(recipient)
    for recipient in cc:
        draft.Recipients.Add(recipient).Type = win32com.client.constants.olCC
    for recipient in bcc:
        draft.Recipients.Add(recipient).Type = win32com.client.constants.olBCC
    draft.Recipients.ResolveAll()
    # Add the subject.
    draft.Subject = subject
    # Add attachments.
    for attachment in attachments:
        assert isinstance(attachment, AttachmentInfo)
        attachment_property_accessor = \
            draft.Attachments.Add(attachment.file_path).PropertyAccessor
        if isinstance(attachment.mime_type, str):
            attachment_property_accessor.SetProperty(
                "http://schemas.microsoft.com/mapi/proptag/0x370E001E",
                attachment.mime_type
            )
        if isinstance(attachment.id, str):
            attachment_property_accessor.SetProperty(
                "http://schemas.microsoft.com/mapi/proptag/0x3712001E",
                attachment.id
            )
    # Set the e-mail body.
    draft.HTMLBody = body
    # Open the e-mail draft in an Outlook window if it is wanted. This is here
    # because an earlier version of the function did this and did not have the
    # display argument.
    if display:
        draft.Display()
    # The caller can call other methods of the MailItem object.
    # https://docs.microsoft.com/en-us/office/vba/api/outlook.mailitem
    return draft