Some email servers or clients wrap links in a proxy. Due to the length and complexity of the links that are sometimes produced in our email verification flows, some of the services behind these proxies don't handle our links very well. You might get a generic looking 404 or a 500 page.

Workaround

Open https://id.atlassian.com/login/resetpassword and enter your email address (make sure you use the same address that is used in the email that you received with the verification link). You will receive an email with a new, shorter, link that will allow you to verify your email address.

Once you have followed the new link successfully you will be able to access your Cloud site without having to log in again.