16. A computer program product for managing and synchronizing electronic communications having a common topic, the computer program product comprising: one or more computer-readable hardware storage media and program instructions stored on at least one of the one or more computer-readable hardware storage media, the program instructions comprising: program instructions to detect a first electronic communication on a first electronic communication medium involving a first user and a first set of one or more users; program instructions to analyze message content of the first electronic communication to identify a first topic of the first electronic communication; program instructions to detect a second electronic communication on a second electronic communication medium involving the first user and a second set of one or more users that has been brought into active view on a user interface of the computer system, wherein the first set of one or more users and the second set of one or more users are each a different set of one or more users; program instructions to analyze message content of the second electronic communication to identify a second topic of the second electronic communication; program instructions to determine whether the first topic matches the second topic; program instructions to determine that at least one user of the second set of one or more users does not exist in a first contact list associated with the first electronic communication medium and that at least one user of the first set of one or more users does not exist in a second contact list associated with the second electronic communication medium; program instructions to identify a third electronic communication medium that can be accessed by the first user, the first set of one or more users, and the second set of one or more users, based on electronic communication mediums known to be accessible to the first user, the first set of one or more users, and the second set of one or more users; and program instructions to, responsive to the first topic matching the second topic, provide to the first user an option to initiate a third electronic communication in the third electronic communication medium involving the first user, the first set of one or more users, and the second set of one or more users, wherein the first electronic communication medium, the second electronic communication medium, and the third electronic communication medium are each a different type of electronic communication medium.
16. A computer program product for managing and synchronizing electronic communications having a common topic, the computer program product comprising: one or more computer-readable hardware storage media and program instructions stored on at least one of the one or more computer-readable hardware storage media, the program instructions comprising: program instructions to detect a first electronic communication on a first electronic communication medium involving a first user and a first set of one or more users; program instructions to analyze message content of the first electronic communication to identify a first topic of the first electronic communication; program instructions to detect a second electronic communication on a second electronic communication medium involving the first user and a second set of one or more users that has been brought into active view on a user interface of the computer system, wherein the first set of one or more users and the second set of one or more users are each a different set of one or more users; program instructions to analyze message content of the second electronic communication to identify a second topic of the second electronic communication; program instructions to determine whether the first topic matches the second topic; program instructions to determine that at least one user of the second set of one or more users does not exist in a first contact list associated with the first electronic communication medium and that at least one user of the first set of one or more users does not exist in a second contact list associated with the second electronic communication medium; program instructions to identify a third electronic communication medium that can be accessed by the first user, the first set of one or more users, and the second set of one or more users, based on electronic communication mediums known to be accessible to the first user, the first set of one or more users, and the second set of one or more users; and program instructions to, responsive to the first topic matching the second topic, provide to the first user an option to initiate a third electronic communication in the third electronic communication medium involving the first user, the first set of one or more users, and the second set of one or more users, wherein the first electronic communication medium, the second electronic communication medium, and the third electronic communication medium are each a different type of electronic communication medium. 20. The computer program product of claim 16 , wherein program instructions to provide to the first user an option to initiate the third electronic communication in the third electronic communication medium involving the first user, the first set of one or more users, and the second set of one or more users comprise: program instructions to cause a graphical notification prompt to be displayed in-line with a section of the first electronic communication containing text pertaining to the first topic, wherein the graphical notification prompt includes an option to initiate the third electronic communication in the third electronic communication medium.