Proofpoint has a very good interview process. Everything starts with the recruiter. After the recruiter I talked to the hiring manager to make sure we are on the same page what the job would require. After talking the the hiring manager you'll go through a technical screening which was basic email and network security questions. After this you'll talk to other team members before you get invited to visit their campus. The onsite interview is great. You'll present the solution via some homemade slides and answer question in a mock meeting. Very helpful to understand what you get ask in the job as well as it shows the team how you respond. After this I only quickly synced with the hiring mangers manager to make sure we are a good fit for each other. That's pretty much it. Not too difficult if you know your stuff. The recruiter was really outstanding on this one and always kept me in the loop and answered questions instantly