我們項目中log4j為我們輸出很多錯誤日志，由于沒有及時處理，造成系統運行不穩定，所以可以將錯誤日志通過郵件形式發送給具體開發人員

1.配置log4j.properties

#DEV
log4j.rootLogger =DEBUG,stdout

RUNING
log4j.rootLogger =INFO,I,E,A5
Console output...
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss}||%F||%M||%m%n
INFO
log4j.appender.I =org.apache.log4j.DailyRollingFileAppender
log4j.appender.I.File =/home/logs/info.log
log4j.appender.I.Append =true
log4j.appender.I.Threshold =info
log4j.appender.I.layout =org.apache.log4j.PatternLayout
log4j.appender.I.layout.ConversionPattern =%d{yyyy-MM-dd HH:mm:ss}||%F||%M||%m%n
ERROR
log4j.appender.E =org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =/home/logs/error.log
log4j.appender.E.Append =true
log4j.appender.E.Threshold =error
log4j.appender.E.layout =org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern =%d{yyyy-MM-dd HH:mm:ss} %m%n
EMAIL
log4j.appender.A5=org.apache.log4j.net.SMTPAppender
 log4j.appender.A5.BufferSize=5
 log4j.appender.A5.Threshold=error
 log4j.appender.A5.To=[被發送者]
 log4j.appender.A5.From=[發送者]
 log4j.appender.A5.Subject=ErrorLog
 log4j.appender.A5.SMTPHost=[STMP服務]
 log4j.appender.A5.SMTPUsername=[用戶名]
 log4j.appender.A5.SMTPPassword=[密碼]
 log4j.appender.A5.layout=org.apache.log4j.PatternLayout
 log4j.appender.A5.layout.ConversionPattern=%-4r %-5p [%t] %37c %3x - %m%n</pre>

來自：http://my.oschina.net/guoenzhou/blog/526626