It is nice to receive an e-mail message telling me when there is a posting in a thread that I am following in MaplePrimes.
When I click on the link in the e-mail, I am taken to a page that reports "Access Denied" (when I am not logged onto MaplePrimes). I do not know what happen if am logged in. There is no indication that the problem is that I am not logged in. I would find it much more informative (and friendly) if the response from the MaplePrimes site was to ask me to log in (showing the login window by default). Assuming successful authentication, I should then be taken to the page with the message.
On a related note, I find the list of messages in my inbox a little confusing. The sender's name and the subject run together and these two fields are different hyperlinks with different targets. It should be clearer that there are two separate fields (gridlines might be helpful).