A) I received an email and it ended with this sentence: Please let me know if there is anything else.
Do I need to reply if I do not have anything to reply? Is is rude if I do not reply anything because I do not have anything to reply? If a reply is needed even if I do not have anything to say, what should be an appropriate reply? Should I reply "That's all"?
B) Sometimes I see this at the end of the email or article:
B1) Let me know what you think
B2) Let me know if you are interested
B1) If I do not have any opinion, do I need to reply? Is it rude if I do not reply?
B2) If I am not interested, do I need to reply? Is it rude if I do not reply?