Remote Server returned ' 420 4.2.0 Recipient deferred because there is no Mdb '

Deferrable keyword in sql
Usually the NDR gives us a clear indication of the error.

Sql deferrable

Today, I am talking about a problem in my daily operations, first of all, my environment is "single-domain multisite" mode, a total of 3 site Exchange, the recipient stream is Exchange Online Protection---A site Cas---a site MBX---The corresponding pickup address database.



According to the NDR, it was found that after the message came down from EOP, the MBX in a site repeatedly jumped and the straights failed completely. After the ECP, ADSI check, found that a site did not correctly synchronize the other two site DC user attributes (HomeMDB)






There are two ways to solve this problem:






1, manual synchronization with other DCs






2. Manually copy this property






For each site DC is not properly synchronized, it does not expand here



This article from "Zhao called Beast" blog, declined reprint!





Remote Server returned ' 420 4.2.0 Recipient deferred because there is no Mdb '