Exchange 2019 CU8 Connectivity Issues

Question

Hello, we are running Exchange 2019 CU8 in a 2 node DAG with 300+ mailboxes. We have just recently upgraded from 2013 in March because of the zero-day exploit. The migration went well, but we are now having intermittent connectivity issues with slow sync speeds.

Here are the issues that have been reported:

Outlook on Windows - messages getting stuck in the Outbox.
Outlook on Mac users are getting "An unknown error has occurred in Outlook." "Mail could not be sent." "Error code: -17884" - This happens a lot.
OWA will show all folders and sub-folders, but the Outlook application does not.
Sending emails with attachment (nothing that large) take over a minute and sometimes fail.
In general, folder syncs seem to be a lot slower.

I have checked and made sure that all FQDNs are correct for all virtual directories and Outlook Anywhere.
I have checked and made sure that MAPI over HTTP is enabled for everyone.
I have run the Healthchecker.ps1, and everything looks good.

I am running out of ideas here. I was debating about updating to CU9, but I wanted to make this post first and see what recommendations we get.

I really appreciate any help you can provide,
Michael

Answer 1

Hi @Michael Houston ,

Agree with Andy, it should be EWS that is used for MAC/iPhone/iPad.

For the errors on MAC Outlook client, please refer to the following article:
Outlook 2016 for Mac - Multiple Issues, Error 17884
And please try set the Throttling policy for EWS to unlimited for these users.

Hope these could help.

Best regards,
Lou

---

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Thanks Lou and Andy,

I am planning on changing the default throttle policy for all users, but wasn't sure which parameter name to edit and to what values to have.

Michael

Answer 3

I have created my own throttle policy and assigned it to all of our users, but we are still having issues with Apple devices.

I made RCAMaxConcurrency, EWSMaxConcurrency, EWSMaxSubscriptions, CPAMaxConcurrency, EwsCutoffBalance, EwsMaxBurst, and EwsRechargeRate all unlimited. What other parameters should I change?

Here is the current policy

RunspaceId : eccc2d98-dd6e-44c7-b753-ade0386201f5
ThrottlingPolicyScope : Regular
IsServiceAccount : False
AnonymousMaxConcurrency : 1
AnonymousMaxBurst : 120000
AnonymousRechargeRate : 420000
AnonymousCutoffBalance : 720000
AnonymousCostThreshold :
BookingSelfServiceMaxConcurrency : 10
BookingSelfServiceMaxBurst : 500000
BookingSelfServiceRechargeRate : 1800000
BookingSelfServiceCutoffBalance : 3000000
ConsensusMaxConcurrency : 10
ConsensusMaxBurst : 500000
ConsensusRechargeRate : 1800000
ConsensusCutoffBalance : 3000000
SchedulesMaxConcurrency : 5
SchedulesMaxBurst : 500000
SchedulesRechargeRate : 1800000
SchedulesCutoffBalance : 3000000
EasMaxConcurrency : 10
EasMaxBurst : 480000
EasRechargeRate : 1800000
EasCutoffBalance : 600000
EasMaxDevices : 100
EasMaxDeviceDeletesPerMonth : Unlimited
EasMaxInactivityForDeviceCleanup : Unlimited
EwsCostThreshold : 50
EwsMaxConcurrency : Unlimited
EwsMaxBurst : Unlimited
EwsRechargeRate : Unlimited
EwsCutoffBalance : Unlimited
EwsMaxSubscriptions : Unlimited
ImapMaxConcurrency : Unlimited
ImapMaxBurst : 3600000
ImapRechargeRate : 600000
ImapCutoffBalance : Unlimited
OutlookServiceMaxConcurrency : 27
OutlookServiceMaxBurst : 300000
OutlookServiceRechargeRate : 900000
OutlookServiceCutoffBalance : 3000000
OutlookServiceMaxSubscriptions : 5000
OutlookServiceMaxSocketConnectionsPerDevice : 9
OutlookServiceMaxSocketConnectionsPerUser : 12
OwaMaxConcurrency : 20
OwaMaxBurst : 480000
OwaRechargeRate : 1800000
OwaCutoffBalance : 0
OwaVoiceMaxConcurrency : 3
OwaVoiceMaxBurst : 75000
OwaVoiceRechargeRate : 375000
OwaVoiceCutoffBalance : 525000
PopMaxConcurrency : 20
PopMaxBurst : 3600000
PopRechargeRate : 600000
PopCutoffBalance : Unlimited
PowerShellMaxConcurrency : 18
PowerShellMaxBurst : Unlimited
PowerShellRechargeRate : Unlimited
PowerShellCutoffBalance : Unlimited
PowerShellMaxTenantConcurrency :
PowerShellMaxOperations : Unlimited
PowerShellMaxCmdletsTimePeriod : Unlimited
ExchangeMaxCmdlets : Unlimited
PowerShellMaxCmdletQueueDepth : Unlimited
PowerShellMaxDestructiveCmdlets : Unlimited
PowerShellMaxDestructiveCmdletsTimePeriod : Unlimited
PowerShellMaxCmdlets : Unlimited
PowerShellMaxRunspaces : Unlimited
PowerShellMaxTenantRunspaces :
PowerShellMaxRunspacesTimePeriod : Unlimited
PswsMaxConcurrency : 18
PswsMaxRequest : Unlimited
PswsMaxRequestTimePeriod : Unlimited
RcaMaxConcurrency : Unlimited
RcaMaxBurst : 150000
RcaRechargeRate : 900000
RcaCutoffBalance : Unlimited
CpaMaxConcurrency : Unlimited
CpaMaxBurst : Unlimited
CpaRechargeRate : Unlimited
CpaCutoffBalance : Unlimited
RcaSharedMaxConcurrency : Unlimited
RcaSharedMaxBurst : 600000
RcaSharedRechargeRate : 3600000
RcaSharedCutoffBalance : Unlimited
MessageRateLimit : Unlimited
RecipientRateLimit : Unlimited
ForwardeeLimit : Unlimited
DiscoveryMaxConcurrency : 2
DiscoveryMaxMailboxes : 5000
DiscoveryMaxKeywords : 500
DiscoveryMaxPreviewSearchMailboxes : 5000
DiscoveryMaxStatsSearchMailboxes : 100
DiscoveryPreviewSearchResultsPageSize : 200
DiscoveryMaxKeywordsPerPage : 25
DiscoveryMaxRefinerResults : 10
DiscoveryMaxSearchQueueDepth : 32
DiscoverySearchTimeoutPeriod : 10
PushNotificationMaxConcurrency : 20
PushNotificationMaxBurst : Unlimited
PushNotificationRechargeRate : Unlimited
PushNotificationCutoffBalance : Unlimited
PushNotificationMaxBurstPerDevice : 10
PushNotificationRechargeRatePerDevice : 6
PushNotificationSamplingPeriodPerDevice : 600000
EncryptionSenderMaxConcurrency : 200
EncryptionSenderMaxBurst : 4800000
EncryptionSenderRechargeRate : 18000000
EncryptionSenderCutoffBalance : Unlimited
EncryptionRecipientMaxConcurrency : 20
EncryptionRecipientMaxBurst : 480000
EncryptionRecipientRechargeRate : 1800000
EncryptionRecipientCutoffBalance : Unlimited
ComplianceMaxExpansionDGRecipients : 10000
ComplianceMaxExpansionNestedDGs : 25
SuiteMaxConcurrency : 20
SuiteMaxBurst : 480000
SuiteRechargeRate : 1800000
SuiteCutoffBalance : Unlimited
IsLegacyDefault : False
Diagnostics :
AdminDisplayName :
ExchangeVersion : 0.20 (15.0.0.0)
Name : AllUsers
DistinguishedName : REMOVED
Identity : AllUsers
Guid : 85b9e232-2c3e-45cb-be54-c9aabb2aaf33
ObjectCategory : REMOVED/Configuration/Schema/ms-Exch-Throttling-Policy
ObjectClass : {top, msExchGenericPolicy, msExchThrottlingPolicy}
WhenChanged : 5/27/2021 12:58:42 PM
WhenCreated : 5/27/2021 12:56:46 PM
WhenChangedUTC : 5/27/2021 4:58:42 PM
WhenCreatedUTC : 5/27/2021 4:56:46 PM
OrganizationId :
Id : AllUsers
OriginatingServer : REMOVED
IsValid : True
ObjectState : Changed

Answer 4

No I mean Apple devices. Outlook on Windows is working a lot better.

We are still having long delays and message getting stuck in the Outbox in Apple Mail and Outlook on a Mac.

Is that still the EAS settings in throttling?

Also, what is the "UInt32" value in your last comment? I am not seeing that value used anywhere.

Answer 5

I think this isn't the throttle policy. I created a new policy and set almost every parameter to unlimited and assigned it to a test user and we are still having issues.