Gmail SMTP relay with Postfix

The following configuration has been performed in Debian but should apply in any Linux distro with Postfix installation. The task quite simple: use Gmail as SMTP relay for outgoing email traffic.

1) At first place I had to install the following packages and turn off sendmail:

apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
service sendmail stop

2) Then edit the configuration file at /etc/postfix/main.cf by adding the following options at the end of the file:

# Gmail SMTP relay
relayhost = [smtp.gmail.com]:587
smtp_use_tls=yes
smtp_sasl_auth_enable = yes 
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_sasl_security_options =

3) Create the authentication file at /etc/postfix/sasl_passwd and set the right permissions:

[smtp.gmail.com]:587    <username>@gmail.com:<password>
chmod 400 /etc/postfix/sasl_passwd

Make sure the file is owned by the user who runs the Postfix daemon.
4) Reload Postfix:

service postfix reload

5) Confirm the configuration is actually working by sending a test mail:

echo "Test mail from postfix" | mail -s "Test Postfix" pkritikakos@isbs.gr

The sender of the email should be the given Gmail account. Also, in the “Sent” folder of the Gmail account you should see the email you have sent with Postfix.

If your domain is using Gmail’s infrastructure for handling emails, you can replace @gmail.com with your domain and use the corresponding account details.

NOTE: This configuration will be sending any system message as “username@gmail.com” and therefore is not advised to be used in multi-user environment.

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Java HTTP library

Being in need to issue POST requests from within a Java application, and wanting re-usable code, I created a very simple Java library for issuing POST and GET requests to a remote server.

POST source code – GET source code

Usage (POST example):

POST post = new POST();
post.postRequest("http://www.myservice.com/service", "param1=foo&param2=bar", "Mozilla/5.0");

In other words, the arguments are:

post.postRequest(SERVER_URL, PARAMETERS, AGENT);

The output can be manipulated as desired, depending on what you response you except you should use a corresponding element/object.

Java libary in Android project

If you have developed your Java library that you would like to use within your Android project, or you want to use an existing Java library, make sure that the library itself is compiled with Java 1.6 rather than 1.7. Have been always forgetting that and have wondering for a couple of days why am I getting “NoClassDefFoundError” error.