What can I do to help him?

Nineteen years ago I gave my newborn son up for adoption. I chose the
adoptive parents through a private lawyer. It was a closed adoption, but was
told that they were a open and honest family. I was told at the time of the
adoption that he would be told that when he turned eighteen, if he wanted,
the adoptive parents would find me for him to meet. In May of 2007 the
adoptive mother found me, called me and told me that he had turned eighteen
and had asked her to find me, he would like to meet. I agreed and said I
would make myself available whenever it was convenient for them. She said
that she hadn\'t expected to find me so quickly and to give her some time
before she told him that she had found me. She didn\'t know if he was ready
yet. I again told her that I would be available whenever the time was right.
I had no further contact with her until April of 2008. The adoptive mother
once again called me and told me that she had never told her son that she
had found me before, but nearing his nineteenth birthday he had asked again
for her to find me. We talked on the telephone for almost an hour. We
exchanged e-mail adresses and dicussed several meeting times and places, all
of which she could not or would not agree on. So once again I told her that
I would make myself available whenever and where ever it was convenient for
him. At the end of the phone conversation she told me that she wasn\'t going
to tell him that she had found me or that we had talked. In fact he didn\'t
even know my name, but she would send a picture of him to my e-mail and
would like one in return of me. I havn\'t heard from her since the exchange
of pictures.
I do not want to be intrusive, but I feel that if he wants to meet with
me to satisfy his curiosity he should be able to do so, considering that he
is legally an adult now. I honestly don\'t know if she will tell him that
she has found me twice now.
Question: How can I legally and unobtrusively give him the means to
contact me on his own?

[In May of 2007 the
adoptive mother found me, called me and told me that he had turned eighteen
and had asked her to find me, he would like to meet]

It would seem given the above that you do have some right to be a little more persistent about this at this point. You might just call her or email and say you want this to occur or will consider legal action, now that she has opened this up.