Send asynchronous emails in Magento 1.6

Question

In Magento how to send emails (order, new user etc) asynchronously?

In my production instance calls like $mailer->send(); takes around 40 to 60 seconds.

Answer 1

I ended up using Redis for queuing mechanism, where in mail details would be pushed to Redis list based queue (using lpush command) and poped at the worker (using brpop command)