We have a new Craft site that includes front-end member registration. We've heard from the client that many of the activation emails are getting stuck in spam filters (and I just tested with the same result). Is there anything that we can do to avoid this? Perhaps add SPF records?
This the best article I've read on reliably delivering emails through code: http://blog.codinghorror.com/so-youd-like-to-send-some-email-through-code/