Cultural tip on kindness

Hello there,

I need help please with a cultural issue.

When I send a document by email to a client, I usually get two types of reply:

A) Got it. Thanks.

B) Thank you so much! It's absolutely perfect.

So, for all the replies within category "A" above, I understand the conversation is ended.

However, for the replies within category "B", I feel like I must end the conversation with a reply to the kind reply, something like "You are so very welcome! If you need any help, feel free to reach me. Regards, X."

Is it necessary or, even if not, is it desired (by the client)?

Thanks!