Appointments do not sync from Dynamics 365 to Exchange for some users

Appointments do not sync from Dynamics 365 to Microsoft Exchange for some users. If you view the Alerts section for a corresponding mailbox in Dynamics 365, you see the following alert message:

"Appointments, contacts, and tasks for the mailbox <Mailbox Name> couldn't be synchronized. The owner of the associated email server profile <Profile Name> has been notified. The system will try again later.

Email Server Error Code: Exchange.server returned 383 error."

Microsoft is aware of an issue with the Exchange Web Services API that can cause this error if one of the following time zones are used:

• (GMT-05:00) Chetumal - Eastern Standard Time (Mexico)
• (GMT-03:00) Montevideo - Montevideo Standard Time
• (GMT+01:00) Casablanca - Morocco Standard Time
• (GMT+02:00) Cairo - Egypt Standard Time
• (GMT+02:00) Kaliningrad - Kaliningrad Standard Time
• (GMT+02:00) Windhoek - Namibia Standard Time
• (UTC+02:00) Khartoum - Sudan Standard Time
• (GMT+03:00) Baghdad - Arabic Standard Time
• (GMT+03:00) Istanbul - Turkey Standard Time
• (GMT+03:00) Minsk - Belarus Standard Time
• (GMT+04:00) Astrakhan, Ulyanovsk - Astrakhan Standard Time
• (GMT+04:00) Baku - Azerbaijan Standard Time​
• (GMT+04:00) Izhevsk, Samara - Russia Time Zone 3
• (GMT+04:00) Moscow, St. Petersburg, Volgograd - Russian Standard Time
• (GMT+04:00) Yerevan - Caucasus Standard Time
• (GMT+05:00) Ekaterinburg - Ekaterinburg Standard Time
• (GMT+07:00) Barnaul, Gorno-Altaysk - Altai Standard Time
• (GMT+07:00) Hovd - W. Mongolia Standard Time
• (GMT+07:00) Krasnoyarsk - North Asia Standard Time
• (GMT+07:00) Novosibirsk - N. Central Asia Standard Time
• (GMT+07:00) Tomsk - Omsk Standard Time
• (GMT+07:00) Tomsk - Tomsk Standard Time
• (GMT+08:00) Irkutsk - North Asia East Standard Time
• (GMT+09:00) Chita - Transbaikal Standard Time
• (GMT+09:00) Yakutsk - Yakutsk Standard Time
• (GMT+10:00) Vladivostok - Vladivostok Standard Time
• (GMT+11:00) Bougainville Island - Bougainville Standard Time
• (GMT+11:00) Chokurdakh - Russia Time Zone 10
• (GMT+11:00) Magadan - Magadan Standard Time
• (GMT+11:00) Norfolk Island - Norfolk Standard Time
• (GMT+11:00) Sakhalin - Sakhalin Standard Time
• (GMT+12:00) Anadyr, Petropavlovsk-Kamchatsky - Russia Time Zone 11

Microsoft is investigation a solution to this issue. In the meantime, you can work around the issue by changing the user's time zone setting in Dynamics 365:

1. A Dynamics 365 user can access their personal options by clicking the gear icon in the upper-right corner of Dynamics 365 and then clicking Options.
2. If the Time Zone value is one of the time zones listed in the Cause section above, update the value to another time zone that has the same time offset but is not in the list within the Cause section of this article. 
   
   For example: If you are using (GMT-05:00) Chetumal, you could try switching to (GMT-05:00) Havana.
3. Click OK.
4. The appointments should sync on the next sync cycle for the mailbox which may take 15-30 minutes.