write_email_message_to_file
='preview_email.html') write_email_message_to_file(msg, out_file
Writes the HTML content of an email message to a file, inlining any images referenced by Content-ID (cid).
This function extracts all attachments referenced by Content-ID from the given EmailMessage, replaces any src="cid:..."
references in the HTML body with base64-encoded image data, and writes the resulting HTML to the specified output file.
Params: msg The email message object containing the HTML body and attachments. out_file The path to the output HTML file.
Returns: None