We will always handle incoming mail coming back to your site. We have to in order to process the comments.
When we launch 1.0 we will no longer offer free outgoing mail service. We really wish we could but the cost would be exorbitant. If you are running a small site or are on a quality host and behaving yourself, you shouldn’t have any problems. If you do have problems we will offer very affordable outgoing mail service as part of a paid upgrade (with lots of other cool features such as analytics and support for post attachments). Once we see how the numbers shake out we’ll come up with the most obtainable price possible.