How to validate email address from mail server?

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validation

email

OpenSSL

Hi All,

i want to validate email id form email server.

example- sample@gmail.com is exist or not.

i want to validate via SMTP Handshakes. so i am using openssl.exe to run command from c# and read and write the coommand in openssl using streamwriter and streamreader. but unavailable to read last line response amd also not unavailable to re-wrte command on openssl command promt.

this is my sample code.

private StreamWriter mOutStream = null;
private StreamReader mInStream = null;

Process newShell = new Process();
newShell.StartInfo.FileName = "openssl.exe";
newShell.StartInfo.Arguments = " s_client -starttls smtp -crlf -connect smtp.gmail.com:587";
newShell.StartInfo.RedirectStandardInput = true;
newShell.StartInfo.RedirectStandardOutput = true;
newShell.StartInfo.UseShellExecute = false;
newShell.Start();
mOutStream = newShell.StandardInput;
mInStream = newShell.StandardOutput;

int read_int;
int x;
while (mInStream.Peek()>0)
{
x = mInStream.Peek();
char[] buffer = new char[4096];
read_int = mInStream.Read(buffer, 0, buffer.Length);
for (int i = 0; i < read_int; i++)
{

line = line + buffer[i];// not reading the last line where response code will recived like 220,250 etc.
}
}
mOutStream.WriteLine("MAIL FROM example.com \r\n"); //here is my email id

not writing on next command on openssl. shall i am doing any thing wrnog.