What's the proper way to run some Python code asynchronously?

I needed to send mail from my plain Flask app, so I thought the simplest way would be to send it using smtplib. But I had to do it asynchronously - you can't just insert a 3 second delay into the request - right? So I add the email to a queue (psql table), and send it from another program that reads this table and uses smptlib. This second program (maildonkey) is running as a separate process, in an independent upstart service. Now I need another one of those little asynchoronous services, and I'm thinking if I should write another python script (third, counting my Flask app and 'maildonkey') or should I use something like Python's 'multiprocess', or even 'threads' and rewrite the second program? (When I was programming in Clojure, I could easily run code in a separate thread with 'futures', so normally I would do that.)