The hard stuff isn't in getting a working mail server running - that's easy, but in getting DNS, etc. setup properly.
In order to host your own mail server, you have to have your own domain, and be able to set the MX record for your domain to point to your IP address.
You then also have to make sure your ISP doesn't block incoming mail servers (something many of them do on residential accounts where running servers is not permitted in the terms of service).
If you can handle that part, you can probably handle the sendmail config easily enough.