Yep. For example I've got my own personal domain for email and my personal site. I also run a Rauthy instance for OICD for my hosted services which sends you an email to sign up after being invited, instead of using my personal domain which Rauthy isn't on I can add the domain to Purelymail and now the emails can come from noreply@rauthy.example. It's a small thing but it looks nice.