How about having a "note-passing" time among your students? I did this last year with my 6th graders as a positive way to respond to the note-passing happening in my classroom. I told them that I noticed how much they loved to write to each other, so I was going to allow them to continue---but with a catch.
My students had to use the friendly letter format, which we had already learned, on paper that I passed out. I allowed them about 10 minutes at the end of the day to write their letters to each other, and then I collected them after they were read. Of course, guidelines were established to curb inappropriate discussions.
My students were very eager to engage in writing notes to each other and looked forward to responding to their notes. In fact, knowing that we "might have time" at the end of the day motivated them to stay on task.
This year, I hope to have a mailbox set up in my classroom (I have yet to find a small one) and allow the kids to keep the friendly letters going