Merge pull request MicrosoftDocs#3432 from markjjo/markjjo-working

updated descriptions for mailbox and optionalinmailbox parameters

Author: chrisda

exchange/exchange-ps/exchange/policy-and-compliance-retention/Get-RetentionPolicyTag.md

@@ -129,7 +129,29 @@ Accept wildcard characters: False
 ```
 
 ### -Mailbox
-The Mailbox parameter isn't available in this release.
+The Mailbox parameter returns the retention tags that are assigned to the retention policy that's applied to the specified mailbox. You can use any value that uniquely identifies the mailbox. For example:
+
+- Name
+
+- Alias
+
+- Distinguished name (DN)
+
+- Canonical DN
+
+- \<domain name\>\\\<account name\>
+
+- Email address
+
+- GUID
+
+- LegacyExchangeDN
+
+- SamAccountName
+
+- User ID or user principal name (UPN)
+
+This parameter only returns default policy tags (DPTs) and personal tags; it doesn't return retention policy tags. 
 
 ```yaml
 Type: MailboxIdParameter
@@ -144,7 +166,9 @@ Accept wildcard characters: False
 ```
 
 ### -OptionalInMailbox
-The OptionalInMailbox parameter isn't available in this release.
+The OptionalInMailbox parameter is used with the Mailbox parameter to return any opt-in retention tags that are assigned to the specified mailbox. You don't need to specify a value with this switch.
+
+An opt-in retention tag is a personal tag that was explicitly assigned to the mailbox with the Set-RetentionPolicyTag -Mailbox -OptionalInMailbox command.
 
 ```yaml
 Type: SwitchParameter

exchange/exchange-ps/exchange/policy-and-compliance-retention/Set-RetentionPolicyTag.md

@@ -385,7 +385,7 @@ Accept wildcard characters: False
 ```
 
 ### -OptionalInMailbox
-The OptionalInMailbox parameter is used with the Mailbox parameter to specify opt-in retention tags available to the mailbox.
+The OptionalInMailbox parameter is used with the Mailbox parameter to assign personal tags to the mailbox. You can use this parameter to make available to a user a personal tag that isn't assigned to the retention policy applied to the specified mailbox. You can specify multiple personal tags separated by commas.
 
 ```yaml
 Type: RetentionPolicyTagIdParameter[]