Hello Marmor, thanks for your great work!
I wasnt able to get this working with yahoo mail, it took me some time to find the point where your implementation was non standard:
SOCK_TCPSEND(socket%, "MAIL FROM: "+from$ +LFCR$)
check()
SOCK_TCPSEND (socket%, "RCPT TO:" +to$ +LFCR$)
check()
This may work with some mail servers, but others may have problems (like yahoo), better make it that way:
SOCK_TCPSEND(socket%, "MAIL FROM:<"+from$ +">"+LFCR$)
check()
SOCK_TCPSEND (socket%, "RCPT TO:<" +to$ +">"+LFCR$)
check()
This works on yahoo servers (tested) and should work without problems on any other server too (testing needed).
I would recommand to change
SOCK_TCPSEND (socket%, "TO : " +to$ +LFCR$)
check()
to
SOCK_TCPSEND (socket%, "From: <" +to$ +">"+LFCR$)
check()
SOCK_TCPSEND (socket%, "To: <" +to$ +">"+LFCR$)
check()
but i thats not needed, more for style.