Emailing Students: yes/no?

I think emailing students in your class is okay if it is for classroom assistance only. Some of these benefit items may include things like homework help and reminders for tests/quizzes/projects. I feel like it is important for your students to have some sort of communication with you if possible. I personally would rather them email me instead of calling me because it would allow me to have a source of documentation right at my hands in case anything were to come up with it. And it also is contributing to the idea of incorporating more technology into the classroom and schools. I think that is important to lay out ground rules though from the beginning. Let the students know that your email is only for school/classroom related business and nothing else. Hopefully this will nip some things in the bud before they start. It would definitely be a drawback if your emailing relationship started to become abused.
I believe it becomes a legal issue when you start to building a "friendship" relationship with your students on line and it is no longer about class. I think it probably starts out very innocent but you never know what could happen when you least expect it.