Oh, so you don't have the source code for something that's currently running, perhaps in production? I'm not used to that situation, having used script languages (well, Perl) for close to twenty years.

I don't currently have the bandwidth to try your code out with my own SMTP service, so at this point all I can suggest is to simplify the problem as much as possible, and turn on whatever verbose/debugging options there are to help you understand which parts are working, and which parts are not working .. for some definition of 'working'.