For people who want to do this, be sure to get it right. I run a SaaS with a free tier, and I see people register with "fancy+nospam+servicename@gmail.com" addresses. Many of those become undeliverable or are left unread forever because of filtering rules. So when my system sends a warning E-mail that the account will be deleted due to inactivity, it doesn't get read, which leads to suboptimal outcomes for everyone involved.