Read the terms and conditions closely to be sure you don’t give up rights you can’t give. For example, Google Gmail’s Terms & Conditions includes this statement in section 11.1: “By submitting, posting or displaying the content you give Google a perpetual, irrevocable, worldwide, royalty-free, and non-exclusive license to reproduce, adapt, modify, translate, publish, publicly perform, publicly display and distribute any Content which you submit, post or display on or through, the Services.” In Section 11.2 is says “You agree that this license includes a right for Google to make such Content available to other companies, organizations or individuals with whom Google has relationships for the provision of syndicated services, and to use such Content in connection with the provision of those services.” Be sure these are conditions you can agree to before using cloud based emails.