Description: Sometimes the SuperOffice MailLink key in the registry can become "corrupt" and makes the Addin in Outlook not visible anymore, while its set to Active and loaded.  A simple reinstall of MailLink does not help, but a clean reinstall (cleaning appdata and registry of SuperOffice keys/files) almost always fixes it. The only thing is that the issue seems to come back and it also happens on terminal servers, where a clean reinstall is not a nice thing to do, as it can happen only for one user. 

Workaround:

1. close outlook
2. Open the registry
3. Delete the whole HKEY_CURRENT_USER/Software/SuperOffice key. 

4. start outlook again. Observe that MailLink is visible again.