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Support Article

Slow performance Email listener, Microsoft Office 365 Outlook



An email listener has been configured to process emails sent to a Microsoft Office 365 Outlook server (Exchange Online). Most of the time, the email listener works as expected, namely, a case is created from the incoming email in just a few seconds. But sometimes the process stalls or hangs, and case creation takes several minutes.

Error Messages

Not Applicable

Steps to Reproduce

Configure an email listener to process email messages from Microsoft Office 365 Outlook.
Refer to this Pega 7.1.6 Help topic,

Root Cause

The PegaRULES logs did not indicate the source of the case creation time lag. No Pega0005 alert issues were reported.
A thread dump and stack trace shows the thread waiting for a response from email server: Nothing unexpected is reported here.

thread dump stack trace indicating cause of time lag

Given these results, a request was submitted to the Microsoft support team to analyze the IMAP logs on the Exchange Online server.
The Microsoft analysis reported a signifcant throttling issue. The only errors seen occurring were caused by the email account being throttled and the fact that one (1) server was not available. The number of operations on this email account is very high; therefore, throttling issues can be expected.


Here is the explanation for the reported behavior:

Microsoft Exchange Online includes bandwidth throttling to help manage server access. This supports service quality and consistent performance. The throttling components of Exchange Online are especially important, given that network resources in the data centers are optimized for the broad set of customers that use the service. Therefore, to properly engineer solutions that work with Exchange Online, you will need to account for the Exchange Online throttling settings.

Unfortunately, for the case reported and described here, the throttling numbers were already set to their maximum levels:
MaxConcurrency 20
MaxTenantConcurrency 100
MaxBurst 900,000
RechargeRate 2,520,000
CutoffBalance 3,000,000
ExchangeMaxCmdlets 200
MaxDestructiveCmdlets 120
PowerShellMaxCmdlets 400
MaxOperations 400

For this particular case, Microsoft Office 365 Outlook was not the best email option for the business needs of the enterprise because the Exchange Online server
performance limits were reached.

When configuring an email listener to work with Micrsosoft Office 365 Outlook, understand how to specify the throttling limits for the Exchange Online server. Contact the Microsoft Office 365 support team to assist you with this task.

Published January 31, 2017 - Updated October 8, 2020

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