While connecting with a NT FTP Server 4.0 with a banner message with several lines the function ftp_login always returns a warning error.
I debug the source code and found a bug on file funcions/ftp.c on function int ftp_getresp(ftpbuf_t *ftp)
If the function receive a blank line the loop below is aborted

while (1) {
    if (!ftp_readline(ftp))
       return 0;
    if (ftp->inbuf[3] == '-')
        continue;
    else if (ftp->inbuf[3] != ' ') 
        return 0;
    break;
}

I think I resolved the problem (it works with my application) adding a line to this loop:

while (1) {
    if (!ftp_readline(ftp))
       return 0;
    if (ftp->inbuf[3] == '-')
        continue;
    else if (ftp->inbuf[0]==0) continue;
    else if (ftp->inbuf[3] != ' ') 
        return 0;
    break;
}


I hope I could help you.

Ulisses Donato