ch.qos.logback.core.util.DynamicClassLoadingException: Failed to instantiate type ch.qos.logback.classic.net.SMTPAppender

Question

I have the following logback.xml in my spring-boot application:

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
       ...
    </appender>

    <timestamp key="datetime" datePattern="yy-MM-dd-HH-mm-ss" />
    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        ...
    </appender>

    <appender name="EMAIL" class="ch.qos.logback.classic.net.SMTPAppender">
        <smtpHost>smtp.gmail.com</smtpHost>
        <smtpPort>587</smtpPort>
        <STARTTLS>true</STARTTLS>
        <username></username>
        <password></password>
        <to>[email protected]</to>
        <from>[email protected]</from>
        <subject>Error</subject>
        <layout class="ch.qos.logback.classic.html.HTMLLayout"/>
        <asynchronousSending>true</asynchronousSending>
        <encoder>
            <pattern>
                %d{dd.MM.yy HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
            </pattern>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="STDOUT" />
        <appender-ref ref="FILE" />
        <appender-ref ref="EMAIL" />
    </root>

</configuration>

Context is not up with error:

java.lang.IllegalStateException: Logback configuration error detected: 
ERROR in ch.qos.logback.core.joran.action.AppenderAction - Could not create an Appender of type [ch.qos.logback.classic.net.SMTPAppender]. ch.qos.logback.core.util.DynamicClassLoadingException: Failed to instantiate type ch.qos.logback.classic.net.SMTPAppender
ERROR in ch.qos.logback.core.joran.spi.Interpreter@22:73 - ActionException in Action for tag [appender] ch.qos.logback.core.joran.spi.ActionException: ch.qos.logback.core.util.DynamicClassLoadingException: Failed to instantiate type ch.qos.logback.classic.net.SMTPAppender
ERROR in ch.qos.logback.core.joran.action.AppenderRefAction - Could not find an appender named [EMAIL]. Did you define it below instead of above in the configuration file?
ERROR in ch.qos.logback.core.joran.action.AppenderRefAction - See http://logback.qos.ch/codes.html#appender_order for more details.
...

What do I wrong?

Solution

compile ('javax.activation:activation:1.1.1')
compile ('javax.mail:mail:1.4.7')

dependencies helped me