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Microsoft 365 - Email and Calendaring - Known Issues

These are the known issues with the Microsoft 365, Exchange Online, beta currently being undertaken by IS&T staff. If you discover any additional issues, please contact the M365 Team at

  • Apple Mail - Apple Mail will not allow you to edit your username or server name on an existing account. You have to delete your old account and create a new one using your full email address This has the unfortunate result that your inbox will need to fully re-sync causing you to have to re-download all your mail stored on the servers. This may take quite some time depending on the size of your inbox. To delete your account and create a new one, see:
  • Apple Mail won't sync new messages - Some users have reported that Apple Mail has stopped syncing new messages, even when specifically requested to sync the mailbox. It will download new messages when the application is first opened or if you toggle the accounts offline and then online again. To toggle the accounts offline and online again:
    1. Go to Mailbox > Take All Accounts Offline
    2. Wait a few seconds.
    3. Go to Mailbox > Take All Accounts Online
  • iPhone calendar and email blank after migration - Double check that you've updated your username. If that doesn't resolve the issue delete your MIT Exchange account (Settings > Mail, contacts, calendar > Your Exchange Account > Delete account (scroll down to the bottom)] and recreate it.
  • O365 web signs me back in when I try to sign out - Some O365 web users find that when they try to sign out of O365 that it takes them through the sign out sequence, then automatically initiates a sign in sequence that delivers them right back where they started. We recommend closing the tab/window and quitting your browser entirely. That will effectively sign you out of O365 and prevent anybody else from being able to access your account from any shared workstations.
  • Delegates - if you have delegates or are a delegate, you must all be on the same system. Delegating does not work between users on Exchange 2010 and O365. Be sure all your delegates and the people for whom you are a delegate migrate at the same time.
  • Mac OS Client Calendar Sharing - "Time, Subject, Location" level sharing permissions are not understood by Mac OS clients (Outlook 2011, 2016 and Apple Calendar/iCal). Use Outlook on the Web or higher level permissions such as "Reviewer" as a workaround.
  • Voice Mail - The Unity voicemail single inbox feature does not function with Microsoft 365. The single inbox feature synchronizes your MITvoip voice mail messages with your MIT Exchange email. Messages that you read or delete in email will be marked as read or deleted within the voice mail system and vice versa. Likewise, the Message Waiting Indicator (MWI) light on your telephone will follow the status of voice mail messages delivered to your email account. The Unity voicemail system has an email forward feature that does work with Microsoft 365. This feature forwards a copy of the voicemail to your email address. Modifications to messages in email are not reflected in voicemail. Message waiting indication will only change once all the messages are listened or deleted from the voicemail system. Your voicemail account will be changed from single inbox to email forwarding with your migration to Microsoft 365 if you have the single inbox feature enabled. Please see the following Knowledge Base article on Unity Single Inbox if you have any questions regarding these features: [What is Unity Single Inbox?]
  • Finding People (email and calendaring) - People still on Exchange 2010 are in the Global Address List (GAL) instead of the MIT Directory when you search for them. If you're having trouble finding somebody, be sure you're searching the Global Address List.
  • Old Notifications - Some users have seen notifications of meetings and calendar events from the past show up shortly after switching to O365. This may be happening because those notifications were never clicked away when they were current and the migration process brought them to the attention of the notification agent. These are annoying, but harmless. Simply click them away. The issue is not known to recur.
  • Duplicate Notifications - Some users on Outlook 2016 for Mac on 10.10.5 have reported getting the same calendar notifications for future events repeatedly. The root cause is unknown, and we are looking into the issue.
  • Office 2013 and 2016 repeated password requests - In spite of being logged in already, some users are frequently prompted to re-enter their password. There are two possible solutions:
    • There is anecdotal evidence that deleting all shared calendars and resource calendars that are on the old exchange system (not Microsoft 365) resolves the issue.
    • Check if the pop-up is asking for your local Windows password instead of your MIT Kerberos Account password. It may be trying to open your Windows Credential Files to save/access your local password stores. If so, enter your local Windows password to resolve the issue.
    • Also try opening the Control Panel --> Credential Manager, Select Windows Credentials --> Select the credentials and change the password.
  • Can't access shared calendars and repeated prompts for password in Outlook 2013 and 2016 has been reported by some users after migration. Deleting all shared calendars and re-adding them seems to resolve this issue.
  • Shared Calendars and Reserving Resources - Because resources (conference rooms, projectors) and shared calendars do not sync actively with Outlook for Mac, you will not see meetings that you’ve created appear in the room. The meeting will still appear to non-O365 users.
  • Rooms list only contains the first 100 rooms - The rooms list is truncated after the first 100 and search does not work as expected with this field. The solution is to open the Scheduling Assistant and invite rooms to your meeting as an attendee.
  • Older Android Devices - May have issues using autodiscovery. If so, you must specify the server as
  • Legacy Browser Compatibility - Microsoft 365 is designed to work with the current version of the Safari, Chrome, and Firefox browsers. Some older versions have limited features or are unusable with O365 apps including Yammer, SharePoint, Outlook on the Web and Microsoft Online. For more information, see Microsoft's Microsoft 365 System Requirements
  • Apple Calendar Error - On MacsOS 10.11.4 and 10.10.5, error with one calendar event which is not saving to the server. Deleting event, deleting the account did not resolve the issue. The team has escalated this issue to Microsoft and is awaiting a response.
  • Outlook 2013 won't start - after migration and updating the username, users are told to restart Outlook for the settings to take effect. Outlook then refuses to restart. Rebooting Windows seems to resolve the issue.
  • El Capitan Outlook Issue - Per user report, in El Capitan, things got a little weird. After confirming a successful upgrade in my phone and on the web app, I still couldn’t switch over in Outlook 365. I tried deleting the account but Outlook became unresponsive. After several attempts and consistent unresponsiveness, I force quit Outlook again then navigated to my user folder (finder, click on go and hold down the option key so the “Library" folder shows and click on that. (screenshot included) From Library go to Containers and find the folder and delete the whole folder. Open Outlook and enter the password. Issue was then solved.
  • Outlook 2011 for Mac Sync Problem - Username format was correct in Accounts however the Microsoft Exchange Server under Advanced settings was pointing to which was wrong. Changed the Exchange Server to which resolved the syncing issue.
  • Outlook 2016 for Mac version 15.21.1 - A recent software update to Outlook to this version has caused numerous issues with Outlook calendaring, the ability to access shared calendars, crashing, and other issues. We recommend not updating to this version until a fix is released.
  • Outlook for Mac Redirect Error Message: An error message similar to the following says Outlook was redirected to a different server to get new account settings. This is normal and harmless. Click Allow.

  • “This message has a digital signature, but it wasn’t verified because the S/MIME control isn’t currently supported for your browser or platform.” - This error happens when you receive a message with a digital signature when using Outlook on the Web with a browser that does not support S/MIME ActiveX control. Most browsers are unable to access messages with digital signatures. Either switch to one that does, a local client (Outlook) or ask the sender to resend the message without the digital signature.
  • Office 2013 Windows not showing Free/Busy information for Meeting Invitees: Try clicking add attendees to invite people to the meeting rather than typing the email address into the invite.
  • Location is not Cambridge, MA: The location set by default on your account is fairly random, and may be related to where some servers hosting your data are located. This can mean weather report settings are inaccurate. To change your location, click on the location and select Add Location to open a window that will let you select the correct one.
  • Appointments auto-created from emails automatically invite all people copied on the email If you don't want the appointment put on everybody's calendar, manually create the meeting in your calendar instead of using the prompt in your email client or Outlook on the Web.

More information

IS&T Contributions

Documentation and information provided by IS&T staff members

Last Modified:

April 12, 2024

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