Hello!

Suppose there are 4 Exchange CAS/MB servers - Exch1-Exch4 - in a single AD site, no DAG exists.

A user with a mailbox on Exch1 sends a message to a user on Exch3.

According to https://technet.microsoft.com/en-us/library/jj657495%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

"The Primary Safety Net exists on the Mailbox server that held the primary message before the message was successfully processed by the Transport service." - as far as I get it in my case the Primary Safety Net is on Exch1.

"The Shadow Safety Net exists on the Mailbox server that held the shadow message. " -

Q1: Which server is supposed to hold the shadow message (Exch2/Exch3/Exch4)?

Q2: In case a user sends a message outside his/her organization  where would the Shadow Safety Net exist?

Message resubmission from Safety Net

Message resubmissions from Safety Net are initiated by the Active Manager component of the Microsoft Exchange Replication service that manages DAGs and mailbox database copies. No manual actions are required to resubmit messages from Safety Net. For more information about Active Manager, see Active Manager.

There are two basic Safety Net message resubmission scenarios:

• After the automatic or manual failover of a mailbox database in a DAG.

• After you active a lagged copy of a mailbox database.

Q3: Does it mean lagged database copies can not exist without Safety Net? In other words, can lagged database copies work if Safety Net is disabled?

Thank you in advance,

Michael

• Edited by MF47 18 hours 8 minutes ago