What is the halachic view of male-female friendships and communication via email and phone (the single female is good friends with both the married male and female).
The nice thing to do would be to contact the male regarding the birthday of his deceased relative and also potentially separately about a new book recommendation–is this ok?
As a rule of thumb- communication is allowed, friendship is not. Communication that leads to friendship is also not allowed.
I hope that clarifies things.
All the best