I tried this solution on Ubuntu.
1. Installation of postfix mail server package.
Open a a terminal and apply following command,
sudo su [Enter Linux password]
apt-get install postfix
Use TAB, UP and DOWN ARROW buttons to move between various selections.
Select no configuration in the post installation screen.
2. Copy the configuration file.
cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf
3. Install following packages too
apt-get install libsasl2-2
apt-get install libsasl2-modules
apt-get install ca-certificates
4. Open the following file and add some lines.
gedit /etc/postfix/main.cf
Add the following lines at the bottom of the file.
relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_use_tls = yes
5. Create a new file to save the gmail password.
gedit /etc/postfix/sasl_passwd
Add the following line in the opened file.
[smtp.gmail.com]:587 urgmailid@gmail.com:yourpassword
Add your gmail user name and password.
6. Change the permission of following file.
chmod 400 /etc/postfix/sasl_passwd
7. Translate the /etc/postfix/sasl_passwd to Postfix lookup tables.
postmap /etc/postfix/sasl_passwd
8. Create the /etc/aliases.db
postalias hash:/etc/aliases
9. Create the /etc/postfix/cacert.pem.
cat /etc/ssl/certs/Equifax_Secure_CA.pem >> /etc/postfix/cacert.pem
10. Restart Postfix.
/etc/init.d/postfix restart
Check the following settings in Koha to start email notices,
Administration > Patron categories > Overdue notice required > Yes
Koha Administration > Patrons > Enhancedmessagingpreferences > Allow
Set Koha > Tools > Overdue Notice/status triggers
Enable email service in Koha
koha-email-enable library
Visit following link to check commands to enable email for Koha,
http://wiki.koha-community.org/wiki/Commands_provided_by_the_Debian_packages#E-mail
Information courtesy
These instructions blindly borrowed from Eureka blog.