Answer
To approve emails from mobile phones for the GFI MailEssentials Spam Quarantine:- Go to <GFI MailEssentials installation folder>\wwwconf\
- Open the file web.config with a text editor like notepad.
- Search for the </location> tag.
- Replace with the following text:
<location path="Pages/Quarantine/approve.aspx">
<system.web>
<authorization>
<allow users="*"/>
</authorization>
</system.web>
</location>
- Save the file.
Note that this will ONLY affect the Approve page.