The easiest way to contact any author is writing directly to her publisher.
If you would direct paper mail directly to AVON, I would appreciate it.
AVON is holding Andre Norton's manuscript for SCENT OF MAGIC and has delayed the printing.
If you write to AVON, a letter of appreciation, well maybe they'll catch on that that ANDRE NORTON has a lot of fans.

If that doesn't work, send me a letter inside a letter (both with envelopes and stamps)
I'll forward the enclosed letter to Andre Norton. Be assured that she will answer.
In the archives at Syracuse U, there are copies of letters from fourth graders, all answered. Even the "Dear Mr. Norton, Please send me a photo."