A concrete conversation is a good start.
Briefly describe your project. You get a personal reply with questions and a suggestion for a first call.
What is it about?
A software project, a website, your servers, CRA preparation or a technical second opinion. A few details are enough, a phone number is not required.
Please do not send sensitive security details such as credentials, unpatched vulnerabilities or internal network plans in your first message. We agree on a secure channel for that.