user can't access her comment in private forum

Hi,
We use SSO for userecho, i.e. user signs in with anturis account. We sometimes get the following complain:

"I received an answer to my previous question through the userecho service. When I click the "click here to comment" link, I get a message saying "this forum is private""

Clearly there is no SSO working from his mail client. Do you think it will make sense to have a kind of auto-login link?