I hear you nana P: )
I think as with most, I get some very interestingly worded inquiries these days.
I think the best policy is to still respond professionally, because you never know who else is reading it. You can still be professional without being over the top, so I try and gauge the vibe of the customer, then respond within the same theme.
For example, doing a lot of business within Australia, I will get quite a lot of inquiries starting with ' Hi mate'
Now I would never respond to an inquiry like that with a Dear Sir or anything, that is a little extreme, and can actually impact the customer's view of doing business with you in a negative way.
Of course I'm not about to start my response with, Gday or anything like that lol, but I will most likely use the customer's first name in those situations.
Being able to read a customer by the words they use is a very helpful marketing technique. If you can respond professionally, but within the same them as they have made the inquiry in, then you are on the way to establishing a very early bond.
What that can do is put the customer at ease, and when a customer is relaxed they find it easier to reach for their credit card : )
I always try and provide more information than what the inquiry relates to, while still keeping it relative to the point.
For example: If some writes and asks me if I accept bank deposit, then I will answer that with my details, as well as what they need to put as the payment reference, the approximate time it take their funds to clear, as well as information like despatch time after the funds have cleared as so on.
A lot of customers ask a question at a time, and covering related topics when responding to an initial inquiry can not only encourage a sale, but can eliminate the time answering the next 5 questions the customer would have sent lol.