1. Microsoft Exchange Recipient Parameters 

The Microsoft Exchange recipient isn't a typical recipient 
object, such as a mailbox, mail user, or mail contact. The 
Microsoft Exchange recipient isn't managed by using the 
typical recipient tools that are found in Microsoft 
Management Console or the Exchange Management Shell. 
However, you can use the Set-OrganizationConfig cmdlet in 
the Exchange Management Shell to perform

 2.Internal and External Delivery of System Messages

When system-generated messages are sent to an external 
sender, the Microsoft Exchange recipient is not used as the 
sender of the message. Instead, the e-mail address that is 
specified by the ExternalPostmasterAddress parameter in the 
Set-TransportServer cmdlet is used. 

3.The Microsoft Exchange Recipient in Cross-Forest Scenarios

this configuration introduces issues if either forest 
allows messages to be sent to the Microsoft Exchange 
recipient by using the 
MicrosoftExchangeRecipientReplyRecipient parameter

Exchange Recipient paraments are valaues/attributes which 
can change exchange recipients message behavior.

Types:

1. MicrosoftExchangeRecipientRecipientEmailAddresses: this 
parameter specifies one or more email address for same 
user.may be internal email associated with external email.

2.MicrosoftExchangeRecipientEmailAddressPolicyEnabled:This 
parameter specifies whether the default e-mail address 
policy is automatically applied to the Microsoft Exchange 
recipient

3.MicrosoftExchangeRecipientPrimarySmtpAddress 

4.MicrosoftExchangeRecipientReplyRecipient