Example configuration:
<log4net>
<appender name="SMTPAppender" type="log4net.Appender.SmtpAppender,log4net">
<bufferSize value="1"/>
<authentication value="Basic" />
<to value="to@example.com" />
...
<filter type="log4net.Filter.FuzzyStringFilter,log4net.Filter.FuzzyStringFilter">
<!-- Only send one fuzzy match email every 300 seconds. Default is 300. -->
<DecaySeconds value="300"/>
<!-- Reject strings that are quite similar - 1.0 is an exact match, .33 is roughly similar. Default is 0.8. -->
<MinimumDiceCoefficient value=".80"/>
</filter>
...
</appender>
<root>
<level value="ALL" />
<appender-ref ref="SMTPAppender" />
</root>
</log4net>