That's what I have read. Elamite is agglutinative from what I have read. Elamite is an language isolate like Ainu, Basque, Sumerian, and Etruscan.
I found some wikiwackypedia stuff on that, but that's verboten.
Possibly was based in part on this:
http://www.governpub.com/Languages-E/Elamite.php
However, it also mentioned this paper by this guy, and luckily it was online:
http://starling.rinet.ru/Texts/elam.pdf
The idea of an affinity apparently originated in 1856, which is around the time when cuneiform was being read. Once cuneiform was cracked as a writing system, almost anything in the writing system could be pronounced. In at least one case, an otherwise unknown language was discovered on a single tablet in the Amarna archive, and translated with the help of context from other tablets in that cache.
Also according to that PDF paper, in its modern form the idea was championed by a scholar in the mid 1970s, and has mostly just sat there since, as no large newly discovered Elamite archive has turned up.