Issue in sending email using PushEmailNotifier

I am using sourcecode of notifier from Bitbucket. I am able to create test environment for stash on my machine but I am not able to configure MailServer settings. Not able to test email from stash. It gives me error Network is unreachable.

Caused by: org.springframework.mail.MailSendException: Mail server connection failed; nested exception is javax.mail.MessagingException: Could not connect to SMTP host: mailhost.company.com, port: 25;
[INFO] [talledLocalContainer] nested exception is:
[INFO] [talledLocalContainer] java.net.SocketException: Network is unreachable: connect. Failed messages: javax.mail.MessagingException: Could not connect to SMTP host: mailhost.company.com, port: 25;
[INFO] [talledLocalContainer] nested exception is:
[INFO] [talledLocalContainer] java.net.SocketException: Network is unreachable: connect
[INFO] [talledLocalContainer] at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:400) ~[spring-context-support-3.2.2.RELEASE.jar:3.2.2.RELEASE]
[INFO] [talledLocalContainer] at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:340) ~[spring-context-support-3.2.2.RELEASE.jar:3.2.2.RELEASE]
[INFO] [talledLocalContainer] at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:355) ~[spring-context-support-3.2.2.RELEASE.jar:3.2.2.RELEASE]
[INFO] [talledLocalContainer] at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:344) ~[spring-context-support-3.2.2.RELEASE.jar:3.2.2.RELEASE]
[INFO] [talledLocalContainer] at com.atlassian.stash.internal.mail.MailServiceImpl.sendMessageSynchronously(MailServiceImpl.java:205) ~[stash-service-impl-2.5.0.jar:na]
[INFO] [talledLocalContainer] ... 220 common frames omitted

Not sure what's going wrong here?