The message about web-page blocking
To protect users from malicious content by clicking in the email link that leads to any external resource, instead of loading the web page, you can see the warning.
Inbox.lv checks links you try to open, based on the list of popular malicious web pages and instead of opening the links shows a warning that the resource that you are trying to visit is not safe. This is necessary in order to draw your attention to the potential risks and allow to estimate how much you really need to see the contents of the opened resource.
The warning may be informational - thus allowing the user to make a decision - to visit a web page or better to avoid it, or may warn of blocking resource - barring all the way to access it.
If you were unable to find answer for your question, please write to firstname.lastname@example.org