There are lots of ways to do this. Postfix is nice but a little heavy. The simplest and most functional way I've found is https://github.com/0xERR0R/mailcatcher since all it does is forward the emails. You can even use a throwaway gmail SMTP so it doesn't get send to spam

Easy to set up on a rpi/cheap VPS, as long as you have a hostname. And while you're there, look for a short domain name so it's fast to type (on credit card kiosks). You can get cheap short non-standard TLD's like .li. I got a 3 character domain for $5 a year, as short as bit.ly, but just for me