At least one of a measure of trust or a measure of spoofing risk associated with a sender of a message is determined. A measure of similarity between an identifier of the sender of the message and an identifier of at least one trusted contact of a recipient of the message is determined. The measure of similarity is combined with at least one of the measure of trust or the measure of spoofing risk to at least in part determine a combined measure of risk associated with the message. Based at least in part on the combined measure of risk associated with the message, a verification action is performed including by automatically providing an inquiry message that requests a response to be provided.