Design is something I find quite difficult, and I usually keep my head in the backend
I really, really, really want to hire a designer so I can stay there, but being self-funded makes that impossible
As for the icons, they are a very tricky subject, I intended to create symbols for major features such as Funnel and Triage and have common icons for everything else, but it seems I've failed there
Which icons don't you like?
My app sends emails (not a competitor). The interface uses proxima nova, but the email rendering is generally in an iframe with default sans-serif or serif font-faces.
If you use sans-serif as the first font-face that will default to Helvetica on Macs and Arial on Windows.
So when you hover over, a tooltip appears underneath the icon?