Well,
At the end I've solved it "by myself"...
I've found a class from PJ Naughter that makes wonders and that works with MFC using SMTP, so problem solved.
You can see the class here:
CSMTPConnection v1.36[
^]. (look at "Contacting the author" where the link to the site where the newest class is stored).
At the end problem solved. :thumbsup: