I had a folder of containing 3400 emails, which would often (not always) crash SimpleMail the first time I tried to view it's contents. After moving 500 emails into another folder it seems to have stopped crashing.
I have attached my GrimReaper Crashlog that I got with v0.33 (OS4 version of course) on my Sam440. I suspect a stack overflow given the huge stack trace!
GrimReaper Crashlog