O365 OUTLOOK STARTUP HANGS

Users using thin client terminals at multiple offices started to experience a severe problem where Outlook would appear to hang

CLIENT: UK INSURANCE COMPANY

CHALLENGE

Our customer has over 1,000 users using thin client terminals at multiple offices around the UK.  They use Office 365 with Outlook mailboxes hosted on office.com.

Users started to experience a severe problem where Outlook would appear to hang when starting. The problem was reported to happen between 06:00 and 11:00 each day, with a peak around 09:00 on Mondays and Tuesdays.

ENVIRONMENT

The key components are as follows:

  • Client PCs and Xen servers using Microsoft Outlook
  • Bluecoat Proxy servers
  • Fortinet Internet firewalls
  • Internet connection
  • Hosted e-mail service (office.com)

The Xen servers, proxy servers and firewalls are based in two corporate data centres.

ANALYSIS

We analysed several examples of the problem and found the following behaviour:

  • When the system worked normally, the client would connect to office.com, exchange data for a few seconds and then close the connection
  • When the problem occurred, the session settled into a pattern where data packets were only received from office.com once per minute:

  • This behaviour continued for over 15 minutes (until the client closed the application)
  • There was no significant difference between the delays seen on the inside and outside of the proxy servers – the proxy servers were not responsible for any of the delay

SOLUTION

The Outlook hang was caused by Outlook connections being throttled:

We packaged up all the diagnostic evidence and our customer presented it to Microsoft.

SOLUTIONS USED ON THIS PROJECT

Performance & Reliability Troubleshooting

Users using thin client terminals at multiple offices started to experience a severe problem where Outlook would appear to hang

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Data Analytics

Users using thin client terminals at multiple offices started to experience a severe problem where Outlook would appear to hang

KNOW MORE