I really hope this isn't the way most people use R. Wouldn't it be better to call out to a python script that pulls in the emails and spits out a CSV, and then load that into R?
Use whatever programming language YOU are most productive in. For me, that's often R, even if there's a language that's "better" for a specific task -- it's not necessarily better when it's in my hands. FWIW, there's a much easier way to do this in R as well (libcurl 7.20.0 and later includes smtp, imap, and pop3 protocols, letting you do this without calling out to jython).
There are lots of Turing complete languages. They all can do anything. There's no need for religion about language in any case. Hell, write your killer web app in LOLCODE for all I care.