Based on the provided legal document, the main legal points are as follows:

1. An unregistered agreement for sale of immovable property is inadmissible as evidence and cannot serve as the basis for a decree for specific performance or for issuing a mandatory injunction to compel registration (!) (!) (!) .

2. The court held that a suit seeking a decree for registration of an unregistered agreement, without first availing the remedies provided under the Registration Act, such as filing a suit under the relevant provisions for registration, is not legally maintainable. The failure to follow the prescribed statutory procedure renders such a suit invalid (!) (!) .

3. The agreement in question was executed solely for obtaining permission from the Income Tax Department and was not intended as a final, legally enforceable contract for sale. Consequently, the agreement does not constitute a legally binding or enforceable contract for transfer of ownership (!) (!) .

4. The agreement to sell, being an unregistered document, is inadmissible in evidence for the purpose of specific performance under the applicable law, and thus, the court cannot decree specific performance based on it (!) (!) .

5. The court emphasized that the proper legal remedy for ensuring registration of a document is to follow the statutory procedures, and failure to do so cannot be circumvented by filing a suit for a mandatory injunction or specific performance without prior registration or adherence to statutory requirements (!) (!) .

6. The court also clarified that the agreement was not a lease agreement or a document exempt from registration, and no evidence suggested that the agreement was executed for purposes other than obtaining permission, which further undermines its enforceability (!) (!) .

7. As a result of these findings, the court set aside the decree for mandatory injunction and specific performance, and instead, decreed the suit for the refund of earnest money with interest. The interest was awarded at a reasonable rate, considering the circumstances, from the date of the agreement until recovery (!) (!) .

8. The parties were ordered to bear their own costs throughout, and the lower court record was to be returned expeditiously (!) (!) .

In summary, the key legal principles established are that unregistered agreements for sale of immovable property are inadmissible and cannot form the basis for specific performance or mandatory injunctions unless statutory procedures for registration are properly followed. The agreement in this case was deemed executed solely for obtaining permissions, not as a binding sale agreement, leading to the conclusion that the suit for specific performance was not maintainable.