Optimizing lead generation in an online system environment

A non-transitory computer-readable storage medium storing computer program instructions executable by a processor to perform operations comprising:

• receiving, at an online system from a third-party entity a lead generation content item that includes a selectable option;
• sending, by the online system, the lead generation content item to a client device associated with a user of the online system;
• receiving, from the client device, an interaction with the selectable option of the lead generation content item;
• sending, by the online system, an anonymized lead to the third-party entity that the client device interacted with the lead generation content item, wherein the anonymized lead identifies the user by including an anonymized identifier representing the user, the anonymized lead not including the user's personal information;
• receiving, by the online system from the third-party entity, a request that specifies the user, identified by the anonymized identifier, as a recipient of a textual lead message and includes the textual lead message;
• establishing, by the online system, a communication session via an instant messaging system of the online system between the third-party entity and the client device, wherein the user is identified to the third-party entity by the anonymized identifier;
• and
• sending, by the online system to the client device, the textual lead message in the communication session via the instant messaging system.

A system comprising:

• a processor for executing computer program instructions;
• and
• a non-transitory computer-readable storage medium storing computer program instructions executable by the processor to perform operations comprising:
• receiving, at an online system from a third-party entity a lead generation content item that includes a selectable option;
• sending, by the online system, the lead generation content item to a client device associated with a user of the online system;
• receiving, from the client device, an interaction with the selectable option of the lead generation content item;
• sending, by the online system, an anonymized lead to the third-party entity that the client device interacted with the lead generation content item, wherein the anonymized lead identifies the user by including an anonymized identifier representing the user, the anonymized lead not including the user's personal information;
• receiving, by the online system from the third-party entity, a request that specifies the user, identified by the anonymized identifier, as a recipient of a textual lead message and includes the textual lead message;
• establishing, by the online system, a communication session via an instant messaging system of the online system between the third-party entity and the client device, wherein the user is identified to the third-party entity by the anonymized identifier;
• and
• sending, by the online system to the client device, the textual lead message in the communication session via the instant messaging system.