On January 12, 2022, at ~01:49 am UTC, Microsoft communicated via tweet (@MSFT365status) that they were investigating an issue in which users in the UAE were experiencing mailbox access issues.
For IT professionals and system admins with Microsoft admin center access, Microsoft provided three issue #'s: EX313705, EX313731 and MO313750.
Public responses on Twitter confirmed that the issue was impacting many users, but did appear to be self-contained to users in the UAE.
Approximately 1 hour after its first report on Twitter, Microsoft followed up with another brief message that their investigation thus far pointed towards a networking problem as the potential cause. Microsoft was at this time continuing its investigation and network analysis.
Some public responses on Twitter were from users in the UAE who were able to workaround the issue and access their Outlook mailboxes by using personal phones and phone hotspots for their computers.
Several minutes after their previous tweet @MSFT365status, Microsoft reported that their investigation into the issue and cause continued. They also provided an additional incident # (EX313731).
By 4:17 am UTC, Microsoft was reporting that a third-party DNS issue was likely the cause of the Outlook mailbox access issues in the UAE. Microsoft also provided a new (third) incident # (MO313750). The third-party name was never disclosed by Microsoft, but several followers on Twitter reported UAE service providers Etisalat and Du may have been experiencing service issues. Etisalat's own public responses @Etisalat_Care confirmed that Etisalat was experiencing issues as to its own services provided to users in the UAE.
Several hours after their first report @MSFT365status, Microsoft indicated that the impact to users in the appeared to be over. Microsoft was continuing its investigation efforts as to root cause, and they were continuing to monitor service.
At 08:04 am UTC, Microsoft gave its final communication as to the matter, stating that service remained stable and the issue was fully resolved.