stunnel and outlook.com

We are using a program that uses stunnel to connect with Secure Email servers.  We are having problem getting it to connect with outlook.com.  Do you have any knowledge on the use of stunnel or its connection with outlook.com.  We are in contact with the manufatures of program that uses stunnel, but they say it has to do with outlook.  Now I know this is not really the issue because they use stunnel and we don't know how it interacts with outlook.com.  Can you provide any advice?