What is mean by thanks with regards?

Answer is not wrong either. In English grammar, they are thumb rules, however for few cases, it depends on where we use the Words or phrases.

In this case, it can be used when we are requesting another or asking to do a favor or when reporting or informing. Generally, while typing mails or replying or such. this phrase can, however cant be utilized while speech.

Please let me know if in the end of one's mail one can use these expressions

k 4 kusham