Correspondence between Sponsor and Mom? Cancel Title is required

Hello!

We got involved intending for our son to communicate with our sponsored child. We had him "pick out a friend", which is how our boy was chosen. I'd love if it developed into a long-term pen-friend thing. 
Is it culturally appropriate (in Zambia) if I send his mom a note introducing our family and saying we're excited to get to know them?

Thanks!
KKC

That is perfectly fine, especially if the child is younger and would have a volunteer or relative write the letter for him at the start.