@ningji check out the iframely plugin, that might do it.
It would embed a info box, not the entire post.
Let say, I have a site (not a NodeBB site) and it has a newsletter form where users can subscribe by filling in their names & email addresses. After they hit submit, I'd like to redirect to the the forum site (Registration page).
Is it possible to pass variables (eg: email address/username) to Registration page via query string?
For example, https://community.nodebb.org/register?username=jack&[email protected]
What I want to achieve is to since users have filled their information earlier, albeit on a different site, the Registration form should have a prefilled form (ie: name and email address).