Others have done it before and have succeeded with the following main arguments
Internal solutions from large companies usually have 2 main flaws: 1) It’s usually not possible to inviteand create user accounts for customers and partners outside the company. 2) You usually have file size limitations if you are using regular email for your projects.
Working with an online project tool such as GroupCamp is actually more secure than regular corporate email for which all your data is transmitted unencrypted over the public internet All your data is backed up in real time and communication between your browser and the GroupCamp servers is secured with SSL encryption, the same way your bank account is protected.
Your data can be exported at any time with a simple click. You can back up your project data on a regular basis.