I would suggest gmail accounts for a more permanent e-mail.
Recently I discovered an intriguing option for a temporary e-mail address: http://10minutemail.com/10MinuteMail/index.html. You can set them up with a temporary account to access the tool and the e-mail account will simply expire after 10 minutes.
We use Gaggle w/ Google so students can use Google Apps the "educational" version. It is 3 dollars a student. This gets rid of the annoying ads that comes up in Gaggle, plus it filters all of GMail. Another nice feature of Gaggle is the students can blog on there or use message boards, similar to the ones found on here and of course everything is filtered.
As I always say to people Web 2.0 tools are great and cheap (mainly free), you need to find out what your district policy is, because CIPA compliance plays a huge part in student's safety. We have to make sure that we have internet filters in place, and that we are doing everything we can to prevent students from finding inappropriate content, swearing, bullying online, etc etc.
A lot of web 2.0 tools, don't have built in filtering and this really creates an issue if students are posting comments that could potentially be inappropriate.
I am in the same boat. I am currently in the process of setting up the email accounts through gmail. But am still researching how to manage these. I surveyed my students and found the majority have email accounts on their own, or own that their families share that they can use. This made me feel a little better, knowing they already have a social email place. I am wanting to put restrictions on the use of this account (emailing another student - only when collaborating on a project, asking a school work question; emailing teachers questions; and signing up for a web2.0 tool ONLY under the guidelines of a teacher; and no emailing outside our school unless it is a project in which the teacher has approved of who the email is being sent to). I know that this is limiting but at the same time it is just for school purposes and these are younger students.
I tried students' epal accounts just yesterday to get authorization codes for an app I wanted the kids to use and they never got the email. (I wondered if you had to authorize outside emails through epals). Anyway that disappointment has me looking into gmail for students.
This is a real problem in my school--trying to fulfill the technology standard that calls for students to e-mail, and yet have a safe environment in which they can do so.....We tried the free version of Gaggle--but the ads created a problem. This year, there is no funding for the upgraded version.