Free and powerful POP3/SMTP library

I need a library (Delphi or C++ are preferred) that can read mail from POP3 server and send it by SMTP, html’ized mail must be supported (that’s important). The situation is folllowing: there is POP3 mailbox where some people can send email, my progrma must read this mail transorm it a little bit and send it to some other email address.