Everyday I deal with small business owners that tell me "I just use my domain for email" when they call in to renew.
Most times when I try to enquire more about their business and how they brand online they tell me "oh it's all word of mouth" or "we are a very specialized niche market". Or my favorite "I don't need a website."
I ask them to just think about one thing.
When you receive an email from someone you don't know what is the first thing that you do? Do you even open it or do you try to find out more about the company first by googling them? When you can't find them on Google you may not even open it.
This is what you are doing for your clients and associates.
Having even a basic website will ensure your clients know that you are a real company. Without the site you have no way to prove to people that you are who you say you are?
Now if you are dead set against having a website you should at least have the domain name pointing somewhere. A Google my business profile, a Facebook business page or even your LinkedIn profile will do wonders for your business.