On October 18 this issue was separated from a previous incident affecting calendar synchronization for a subset of Office365 client's calendars and escalated for immediate research/remediation. Client reports were of devices sporadically not receiving new events, however forcing a synchronization or renewing a subscription/watch would temporarily resolve the issue. After additional testing and research an adjustment to the frequency and timing of Teem’s automated mechanism to validate and renew these subscriptions/watches was made on October 22. All subscriptions were updated and affected clients were contacted on October 23 after 24 hours of successful monitoring.
Root Cause / Remediation
Office365 via the EWS API will for a variety of reasons, periodically expire subscriptions and Teem has created mechanisms to automatically validate and renew these. Receiving notifications via these subscriptions is how Teem triggers synchronization operations so that new/changed/removed event information is delivered to all Teem tools and devices. Teem adjusted the frequency and algorithms used to ensure valid watches to more aggressively force renewals as necessary and affected calendars have been operating successfully since that time.