Persistent phishing emails after one reply

Hi everyone, I’m dealing with a scammer who just won’t stop emailing me and I’m starting to feel a bit uneasy about it. A while ago, I got an email from someone impersonating my boss asking if I was available. I replied once back then because I didn’t check the email properly. They were trying to get me to buy gift cards, and a quick message to my boss confirmed it wasn’t them. Since then, the same scammer has contacted me multiple times—around 5 to 6 emails now—sometimes from different email addresses. He tries every week or so. I’ve been ignoring and reporting all of them. Today they emailed again and used a different org’s name that I am associated with, which made it feel more targeted and a bit uncomfortable. They keep asking for my phone number or saying they need a quick favour. I haven’t replied since that first time, but I’m confused why they’re being so persistent. All these emails come from the same IP and I have reported to Google and Scamwatch. Has anyone experienced something like this after replying once? Do they eventually stop if you keep ignoring them? Is there anything else I should be doing apart from blocking and reporting? I’m based in Australia if that’s relevant. Thanks