The email itself sounds legit. Check to see if you get emails from people replying to your posts on RF settings.
What I'm going to talk about is the reply rather than the email.
Shrinkme links are simply link shorteners, or links that simply serves as a midpoint between 1 website and the other. When you click on them, I believe you're transported to a website that displays various ads. From there, if you continue, you'll be brought to the website the link is supposed to lead to.
For users, the main goal with link shortners like Shrinkme is to not only to shorten link but to also make money off of clicks. This is because shrinkme is supposed to split revenue gained from the advertisement on the website between them and the person who generated the link 50/50. This means if you click on a link posted by someone, that guy will recieve some money for it.
There are many other websites that function like shrinkme; a classic example is ad fly, which was a pretty popular choice for Minecraft modders as a website link shortner back in the early 2010s.
In my opinion, be carful with them. Since they're link shorteners, you don't really know what you'll be getting into when you click on them, meaning you could unknowingly subject yourself to malware, IP loggers, etc. Additionally, the ads that appear on links of shrinkme can also be harmful as they're often links to scams and viruses. I remember going through an ad fly link and then suddenly transported to a website that tries to get me to call a scammer.
My advice is to stay away from those links as much as possible, but if you have to, I suggest that you should learn how to handle them. Click what needs to be clicked, avoid clicking ads or anything else, and hope that the end destination is safe.
Hope this helps
tl;dr Shrinkme is a monetized links shortener that can be dangerous to click through if you don't know what to click.
