This sounds like Avast is doing its job.
A Trojan horse virus tried to access your computer and Avast caught it. The message and the email address are just to show you the site where the Trojan horse originated.
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But the link is not designed for you to visit. Going to that address is actually a bad thing because that link is the definition of a Trojan horse. You’re going to something related to the malware and it’ll probably try to install something on your machine. And that’s why Avast is blocking you from going there.
Really, the only reason Avast is showing you the link is so you can take note. If you’re visiting a website and the Trojan attacked you from there, maybe the website has been infected. You just want to make sure you don’t go back there until the problem is fixed. You definitely want to keep malware off your machine .