Method for monitoring the value of a parameter indicative of a trust level associated with a first user account of an online service, each user account of the online service comprising user data and a contact means which are associated with one another, allowing a user of said user account to be contacted, the method being executed by at least one server that hosts the online service, the method comprising the steps of: - receiving a first message from a first electronic device connected to the online service with the first user account of the online service, the first message comprising identification data allowing connection to a user account of a social network hosted by at least one server, the user account of the social network comprising a list of other user accounts of the social network that are connected to said user account of the social network, - setting up a connection at least to the server that hosts the social network by using the received identification data, - retrieving, on the server that hosts the social network, user data connected to the other user accounts of the social network that are connected to the account of the social network, and - selecting a second user account of the online service for which at least one value of a predetermined user datum from among the user data of this second user account of the online service is equal to a value of a predetermined user datum from among the retrieved user data of the other user accounts of the social network, - generating a first code for each second user account of the online service, - recording the first code in association with the first user account of the online service, - sending a second message via a contact means associated with the second user account of the online service, the second message comprising the generated first code, and the subsequent steps of: - receiving, from a second electronic device connected to the online service with the first user account of the online service, a third message comprising a second code, - if the second code is equal to the first code recorded in association with the first user account of the online service, then - increasing the value of the parameter indicative of the trust level associated with the first user account of the online service. - receiving a first message from a first electronic device connected to the online service with the first user account of the online service, the first message comprising identification data allowing connection to a user account of a social network hosted by at least one server, the user account of the social network comprising a list of other user accounts of the social network that are connected to said user account of the social network, - setting up a connection at least to the server that hosts the social network by using the received identification data, - retrieving, on the server that hosts the social network, user data connected to the other user accounts of the social network that are connected to the account of the social network, and - selecting a second user account of the online service for which at least one value of a predetermined user datum from among the user data of this second user account of the online service is equal to a value of a predetermined user datum from among the retrieved user data of the other user accounts of the social network, - generating a first code for each second user account of the online service, - recording the first code in association with the first user account of the online service, - sending a second message via a contact means associated with the second user account of the online service, the second message comprising the generated first code, - receiving, from a second electronic device connected to the online service with the first user account of the online service, a third message comprising a second code, - if the second code is equal to the first code recorded in association with the first user account of the online service, then - increasing the value of the parameter indicative of the trust level associated with the first user account of the online service.