Web mail like gmail

General information for the business: I'm after an email platform to offer to my clients instead of web mail like gmail. email platform must be suitable to work on all devices, and I might require android and ios apps for this project. I'm looking for a professional candidate for a long term business Kind of development: New program from scratch Num. of modules: 1 Description of requirements/functionality: I'm after an email platform to offer to my clients instead of web mail like gmail. email platform must be suitable to work on all devices, and I might require android and ios apps for this project. I'm looking for a professional candidate for a long term business Extra notes: I'm after an email platform to offer to my clients instead of web mail like gmail. email platform must be suitable to work on all devices, and I might require android and ios apps for this project. I'm looking for a professional candidate for a long term business