It depends, really. When you're just starting out with sending email from a fresh domain and IP address, you will most likely be flagged no matter what. Do not

It depends, really. When you're just starting out with sending email from a fresh domain and IP address, you will most likely be flagged no matter what. Do not underestimate signals that come from user interaction (e.g. open and click rates). Deliverability is a reputation game.