Recently found my autosupport mail was undelivered.  The config was follow exactly with the working one. So after digging for few days and finally i found the root cause. there is one file *.ems.gz is about 30MB and caused the exchange server to block it. (Thank god 1 of the triggered mail received)

Netapp support had send me the instruction to rotate the log files:

priv set advanced
syslog rotate_syslog
priv set

ta.da……..problem resolved and you are able to receive all autosupport now!