Merge pull request MicrosoftDocs#10538 from guruxp/patch-6

Added the MessageExpiration parameter that is already live and hasn't been included yet on this article.

Author: chrisda

exchange/exchange-ps/exchange/Set-TransportConfig.md

@@ -61,6 +61,7 @@ Set-TransportConfig [[-Identity] <OrganizationIdParameter>]
  [-MaxRetriesForLocalSiteShadow <Int32>]
  [-MaxRetriesForRemoteSiteShadow <Int32>]
  [-MaxSendSize <Unlimited>]
+ [-MessageExpiration <EnhancedTimeSpan>]
  [-QueueDiagnosticsAggregationInterval <EnhancedTimeSpan>]
  [-RejectMessageOnShadowFailure <Boolean>]
  [-ReplyAllStormBlockDurationHours <Int32>]
@@ -964,6 +965,32 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -MessageExpiration
+This parameter is available only in the cloud-based service.
+
+The MessageExpiration parameter specifies the message expiration timeout interval for the organization. 
+
+To specify a value, enter it as a time span: dd.hh:mm:ss where dd = days, hh = hours, mm = minutes, and ss = seconds.
+
+The default value is 1.00:00:00 or 1 day.
+
+A valid value is from 12 hours (0.12:00:00) to 24 hours (1.00:00:00).
+
+Queued messages typically expire after 24 hours, resulting in an NDR for failed delivery. If you change this value, the NDR will be sent at the new applicable time.
+
+```yaml
+Type: EnhancedTimeSpan
+Parameter Sets: (All)
+Aliases:
+Applicable: Exchange Online
+
+Required: False
+Position: Named
+Default value: None
+Accept pipeline input: False
+Accept wildcard characters: False
+```
+
 ### -QueueDiagnosticsAggregationInterval
 This parameter is available only in on-premises Exchange.