# TCP mail client session in Processing not working
**URL:** https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618
**Category:** Libraries
**Created:** [May 26, 2019, 10:10pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618 "2019-05-26T22:10:28Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Birb](https://discourse.processing.org/u/Birb)
#### Post date: [May 26, 2019, 10:10pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/1 "2019-05-26T22:10:28Z")
I’m trying to open a TCP socket with a mail server and then send/read commands, but it isn’t working. After running for several minutes with no response I get the IOException catch error “Couldn’t get I/O for the connection to: hostname”.
```auto
import java.io.*;
import java.net.*;
void setup() {
size(200,200);
Socket smtpSocket = null;
DataOutputStream os = null;
// DataInputStream is = null;
BufferedReader br = null;
try {
smtpSocket = new Socket("64.233.177.26", 25);
os = new DataOutputStream(smtpSocket.getOutputStream());
// is = new DataInputStream(smtpSocket.getInputStream());
br=new BufferedReader(new InputStreamReader(smtpSocket.getInputStream()));
}
catch (UnknownHostException e) {
println("Don't know about host: hostname");
}
catch (IOException e) {
println("Couldn't get I/O for the connection to: hostname");
}
if (smtpSocket != null && os != null && br != null) {
try {
os.writeBytes("HELO Buddy\n");
String responseLine;
while ((responseLine=br.readLine()) != null) {
println("Server: " + responseLine);
if (responseLine.indexOf("Ok") != -1) {
break;
}
}
os.close();
br.close();
smtpSocket.close();
}
catch (UnknownHostException e) {
System.err.println("Trying to connect to unknown host: " + e);
}
catch (IOException e) {
System.err.println("IOException: " + e);
}
}
}
```
The expected output should be : 250 [mx.google.com](http://mx.google.com) at your service
---
### Author:  [@morisil](https://discourse.processing.org/u/morisil)
#### Post date: [May 27, 2019, 8:44pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/2 "2019-05-27T20:44:12Z")
I run this exact code and I got this output:
```auto
Server: 220 mx.google.com ESMTP z9si2024903ybj.299 - gsmtp
Server: 250 mx.google.com at your service
```
---
### Author:  [@Birb](https://discourse.processing.org/u/Birb)
#### Post date: [May 27, 2019, 10:29pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/3 "2019-05-27T22:29:32Z")
Weird, what version of processing? Everything is exactly the same? I wonder why I’m unable to connect.
---
### Author:  [@morisil](https://discourse.processing.org/u/morisil)
#### Post date: [May 27, 2019, 10:43pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/4 "2019-05-27T22:43:56Z")
Processing 3.5.3 on ubuntu linux. I remember that there was one annoying bug with TCP connections on mac initiated from JVM due to timeout with DNS resolution. But usually it was just taking up to 5 seconds instead of milliseconds. What’s your output from this code?
---
### Author:  [@morisil](https://discourse.processing.org/u/morisil)
#### Post date: [May 27, 2019, 10:49pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/5 "2019-05-27T22:49:41Z")
BTW what happens when you do `telnet 64.233.177.26 25` from terminal on the same machine?
---
### Author:  [@Birb](https://discourse.processing.org/u/Birb)
#### Post date: [May 27, 2019, 10:49pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/6 "2019-05-27T22:49:51Z")
I get no output at all, sometimes after a number of minutes it results in the IOexception catch, so the problem seems to be establishing the socket connection. I was thinking it may be my connection, as I’m in China and google is blocked, but I can ping 64.233.177.26 and telnet 64.233.177.26 25 works fine through command prompt. Just to test that theory though, how could I connect through a proxy with sockets?
I should specify I’m also on 3.5.3, but using Windows.
---
### Author:  [@morisil](https://discourse.processing.org/u/morisil)
#### Post date: [May 27, 2019, 10:57pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/7 "2019-05-27T22:57:47Z")
so if you want to debug what’s happening with TCP connections you can use netstat. As far as I remember it works quite similarly on windows. After starting your code I do:
$ netstat -na | grep :25
tcp6 0 0 mylocalip:41150 64.233.177.26:25 ESTABLISHED
If something is wrong with the connection it wouldn’t be established.
---
### Author:  [@morisil](https://discourse.processing.org/u/morisil)
#### Post date: [May 27, 2019, 11:13pm UTC](https://discourse.processing.org/t/tcp-mail-client-session-in-processing-not-working/11618/8 "2019-05-27T23:13:48Z")
You can also try to do `flush()` on the `OutputStream`:
```auto
os.writeBytes("HELO Buddy\n");
os.flush();
```
Or use `PrintWriter` instance with auto flush.