This is interesting because it's something that would likely only happen in production or a staging server. If you're building your web app in development, cha

This is interesting because it's something that would likely only happen in production or a staging server. If you're building your web app in development, chances are your links will have localhost as their hostname which wouldn't trigger a visit from Google. You may also end up having an in memory fake email server to not even send the email in dev too (lots of web frameworks have solutions for this). Checking the user-agent might work but I'm not a fan of this method because now it sets you up with having to keep a list of all known agents for every email client / service that might pre-visit URLs.