We don't recommend using shortened URLs in marketing emails because there are chances for fraudsters to easily use shortened URLs to perform phishing and spoofing activities. Also, ISPs and ESPs may consider emails with shortened URLs to be suspicious.

 

Let's assume that the shortened URL service you use is also used by a spammer. If ISPs and ESPs blacklist the shortened URL's domain and if you keep using the shortened  URL, it will incur negative reputation for your sender domain. This may lead to delivery issues for your emails.