SMG reject some messages with IRCPTACTION msg_reject_other (450 4.3.2 try again later)

SMG 10.5.3-4

Hi,

one user of company didn't receive some mail messages from external user and this external user is getting "450 4.3.2 try again later".

I tried testconnectivity.microsoft.com againts my SMTP and got the same erro message: "450 4.3.2 try again later"

Searching through SMG web based GUI doesn't help so I executed the following: malquery -p 60m -e "IRCPTACTION*msg_reject" and got some entries.

I found this link http://www.symantec.com/business/support/index?pag... and tried to add these IP to "Local Good Sender IPs".

The error message on testconnectivity.microsoft.com went away.

I searched into SMG -> IP reputation lookup -> Local connection history and noticed that 9 are "attempted", 5 are "accepted", and 4 are "deferred".

1) Why deferred ?

2) How can I be aware of these msg_reject messages ?

Any help ?

Thanks.