I just confirmed that RLE compression is not truly implemented in OpenSSL.  It would be helpful to remove it from the stunnel docs so people don�t think it�s an option to compress data.  ZLIB is it. 

 

And yes I spent a good bit of time last year with Wireshark to determine RLE vs ZLIB compression ratios in stunnel.  Shockingly ZLIB was always better�

 

One other note that may be important for some people is that 0.9.7 openssl is not compatible with 0.9.8 with respect to zlib compression.