"Informal inquiries" refers to casual or unofficial requests for information or opinions, without formal procedures or strict protocols. Full definition
The player's agent Hasan Cetinkaya has invited Klopp to bid for his client following an initial, informal enquiry about his availability, which suggests that the player is keen on the idea of a move to Anfield. (koptalk.com)
Send formal service requests with completed application form to [email protected] (informal enquiries prior to proposal submission also welcome) (infrafrontier.eu)
However they are entitled to make informal enquiries. (home-ed.info)