You have so many features using this URL shortener. You also don't need to register to use all feature. Best is to configure your shurt URL with a passwort or set a limit how often it can be called. So you have a very good protection to it.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
shorturl.is - Make long url's short. Statistics included!
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
Capsulink - Capsulink is a URL shortener that gives you the key tools you need to optimize your content and marketing strategies.
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
ShrtFly - ShrtFly is one of the best URL shorteners, They offer Higher Payout Rates on Norway and United States Country.