We use the VPN to present users with various options and one of these is using Outlook Web Access. When users send an email with an attachment the vpn strips it out.
Now, of course you don't need to use the VPN to access OWA but it's there for convenience. Is there a way to stop the attachment being stripped?
Under your Web Profile setting for the OWA access there is a OWA settings section that can control attachment upload/download. Have you checked that?
In the OWA settings prevent attachment download and prevent attachment upload are both unchecked, so not that.