What is the value of the resource you're providing with each signup? Running a regex is only worth it if you're offering value that you have to pay for, like a

What is the value of the resource you're providing with each signup? Running a regex is only worth it if you're offering value that you have to pay for, like a free tshirt or some paid compute credits. And even then, it's only a problem if you have insufficient cash to cover the abuse. If however you're offering LOW COST items (ex: digital goods, or a free month of your SAAS), then absolutely do not filter these. Search for them afterward and contact them. These are some of your most valuable users: people who are willing to put up with the pain of creating new logins over and over again just to use your service. Find out what they love. Find out what it would take for them to start paying. They can provide intelligence far in excess of the free service credits you're providing.