If the SMTP host needs authentication, you can provide your <username> and <password> in the <configuration> section:
<project> ... <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-changes-plugin</artifactId> <version>2.12.1</version> <configuration> <smtpHost>mail.yourhost.com</smtpHost> <smtpPort implementation="java.lang.Integer">25</smtpPort> <username>some@email.com</username> <password>somepassword</password> ... </configuration> </plugin> </plugins> </build> ... </project>