It's as if the sentence is missing something: ""Please feel free to let me know if anything..." is out of order? ...is missing? ...is wrong? A full and correct sentence wold be: "Please feel free to let me know if there is anything that I can do for you" "Please feel free to let me know if there is anything further that I can do for you" I think both of these sentences can be used in formal settings, like a business email.

I have seen it in business emails many times.

Thank you Anup. :)

Expressions for showing them you want to help: you can find in a business email. If I can be of assistance, please do not hesitate to contact me. If you require any further information, feel free to contact me. If you require any further information, let me know. Please feel free to contact me if you need any further information. Please let me know if you have any questions. I hope the above is useful to you. Should you need any further information, please do not hesitate to contact me. Please contact me if there are any problems. Let me know if you need anything else Drop me a line if I can do anything else for you.