Is Setting Up Sub Domain for Email Sends Good Idea?

Is Setting Up Sub Domain for Email Sends Good Idea?

Hi there, our team just bought a dedicated IP for our email sends. We send more than 100k emails/month. Because we face deliverability issues and also because of the mass sends, we decided to get a dedicated IP.

My question is, should we set up subdomains for email sends? What's the ideal option?

What's your take on it? Please help!!!!! 

WE CAN'T DECIDE!