Example
<appender name="AdministratorEmail" class="org.apache.log4j.net.SMTPAppender">
<param name="BufferSize" value="512" />
<param name="SMTPHost" value="some.email.host.org" />
<param name="From" value="appname@server.com" />
<param name="To" value="adminA@server.com,adminB@server.com" />
<param name="Subject" value="SomeApplication on SomeServer12" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="[%d{ISO8601}]%n%n%-5p%n%n%c%n%n%m%n%n" />
</layout>
<filter class="org.apache.log4j.varia.LevelRangeFilter">
<param name="LevelMin" value="error" />
<param name="LevelMax" value="fatal" />
</filter>
</appender>