Ca we use corporate mail for registration and login?

Yes, you should discuss your idea and plans with a lawyer. Here are some questions which I thought of, and I don't even know what your app is about or what industry you're working in. The corporation which hosts the email addresses, owns them. It can review them at will. It can apply filters which will prevent access by you and your company and which will prevent its' employees from emailing to you. In monitoring your communications, if the corporation sees anything it doesn't like, it can so invorm its employees or cut off all contact between its employees and you. What can you offer the corporation in order to obtain its cooperation or at least its non-interference? I can help you set up your company as a corporation or limited liability company. If you're going to need outside investors, I can prepare the documents to make sure you avoid violating applicable securities laws. I can work with you to negotiate and document your cooperation. For example, you may want to use teh corporation's logos and tradenames. If you appreciate this free advice, please remember to refer them to me when they have questions or need help. Referrals are our best source of new clients. Dana Sack