1. A method comprising: determining that a user of a first instant messaging service is associated with a second instant messaging service different from the first instant messaging service; identifying user identities for user other than the user, wherein the user identities are associated with the first instant messaging service and the user identities are stored in a first list associated with the user; determining if at least one of the user identities from the first list of user identities has a matching user identity associated with the second instant messaging service by identifying if a unique portion of the at least one of the user identities from the first list of user identities has at least one common feature with a unique portion of a user identity associated with the second instant messaging service; determining a degree of uniqueness of an identified user identity; adjusting the required amount of common features between the unique portion of the identified user identity and the unique portion of a matching user identity associated with the second instant messaging service based on the determined degree of uniqueness of the identified user identity; and modifying, by a hardware processor, a second list associated with the second instant messaging service to include the matching user identities.
1. A method comprising: determining that a user of a first instant messaging service is associated with a second instant messaging service different from the first instant messaging service; identifying user identities for user other than the user, wherein the user identities are associated with the first instant messaging service and the user identities are stored in a first list associated with the user; determining if at least one of the user identities from the first list of user identities has a matching user identity associated with the second instant messaging service by identifying if a unique portion of the at least one of the user identities from the first list of user identities has at least one common feature with a unique portion of a user identity associated with the second instant messaging service; determining a degree of uniqueness of an identified user identity; adjusting the required amount of common features between the unique portion of the identified user identity and the unique portion of a matching user identity associated with the second instant messaging service based on the determined degree of uniqueness of the identified user identity; and modifying, by a hardware processor, a second list associated with the second instant messaging service to include the matching user identities. 11. The method of claim 1 , wherein at least one of the matching user identities and the identified user identities comprise electronic mail addresses.