Under normal circumstances the CloudFiler icon should appear when you are working with Outlook in a browser or in 'New Outlook'.

If you can't see it. The first thing to do is select the triple-dot menu '...' and you should find it on that list.

Clicking the icon should then display the CloudFiler menu of filing locations.

Outlook sometimes displays the 'Waffle menu' instead, so if that does not work look for the waffle icon in the header of the preview window and pick it:


You should then see CloudFiler in the available list.

If it has disappeared you can easily re-enable it:

Select the Settings cog at the top of the browser, then select  Mail, Customise actions, scroll down to find the section shown below and then make sure that CloudFiler is checked.

Scroll down further to ensure that it's checked for the Toolbar too:

That's it.  CloudFiler should now be available when sending or reading emails from your browser/s.