Can only alumnae write recs?

[sundance]

I don't think I've ever read a recruitment story or anything on here where rec letters didn't come from an alum. One of my good friends is rushing in the fall, and I was wondering if I would be able to write a rec for her. I've known her since we were in diapers, so I feel like I could really speak out about her positive qualities. However, I was just initiated in the spring... so I don't know if my letter would even be of good use.

Are only alumnae allowed to write recommendation letters, or does it not matter if a sister is still active within her chapter? Since I'm on the west coast, I really don't know much about recs!