Fix Outlook for Mac Problems, Full Troubleshooting Guide
Why This Is Happening
I've fielded hundreds of tickets from Mac users who are frustrated, confused, and, honestly, a little embarrassed. They'll say something like "I'm not new to Outlook, I've used it for years on Windows, but on my Mac it just doesn't work the same way." And they're right. It doesn't. And that's not your fault.
Outlook for Mac troubleshooting is its own discipline. The Mac version of Outlook has a separate development history from its Windows counterpart, which means certain features that Windows users take for granted, dragging meetings between calendars, accepting proposed meeting times, sharing sub-calendars freely, are either unavailable, version-gated, or dependent on which server protocol your Exchange account is using. The error messages Outlook throws at you rarely explain any of this. "Not allowed to share this calendar." Why? No idea, right? Except there is a very specific reason, and once you understand it, the fix is obvious.
The issues covered in this guide fall into a few distinct categories. First, there are calendar permission errors, situations where you have owner-level access but still can't share or open a shared calendar. These are almost always tied to either the EWS (Exchange Web Services) protocol limitation or a missing permission on the primary Calendar folder that the sub-calendar lives under. Second, there are meeting workflow limitations, like not being able to accept time proposals or move meetings between calendars, that are deliberate design decisions by Microsoft, not bugs. Third, there are minor but annoying file handling quirks, like JPEG attachments saving with a .jpeg extension instead of .jpg, which trips up users who need exact file extensions for other software.
What makes Outlook for Mac troubleshooting especially tricky is that the version you're running matters enormously. The fix for a missing feature in Outlook 2016 for Mac version 15.8.2 might be as simple as updating to version 15.9 or later. But if you're connected to an older Exchange Server, anything earlier than Exchange Server 2013 Service Pack 1, the update won't help you, because the server-side support isn't there either. It's a two-variable problem, and most people only look at one of them.
The other thing worth knowing up front: Microsoft explicitly classifies some of these behaviors as "by design." That phrase appears in the official documentation more than once. It means Microsoft is not planning to fix it, it's working as intended, even if it doesn't match your expectations. I'll tell you clearly when that's the case and give you the best available workaround instead of sending you on a wild goose chase for a patch that will never come.
If you're dealing with Outlook calendar access denied errors, shared calendar permission failures, or a general inability to perform actions you could do on Outlook for Windows, you're in the right place. Browse all Microsoft fix guides →
The Quick Fix, Try This First
Before anything else, check your Outlook for Mac version number. A significant number of Outlook for Mac problems, especially around the Propose New Time feature and shared calendar access, are version-specific. Here's how to check it:
- Open Outlook on your Mac.
- Click the Outlook menu in the top-left of your screen (next to the Apple logo).
- Select About Outlook.
- Look at the version number shown at the top of that dialog.
If you're on Outlook 2016 for Mac and your version is 15.8.2 or earlier, you're running a build that's missing the Propose New Time feature entirely. Update to version 15.9 or later and a large class of meeting-related problems disappear immediately. To update: go to Help > Check for Updates and let Microsoft AutoUpdate run. Restart Outlook when it finishes.
Second thing to check: which protocol your account is using. Microsoft 365 accounts (formerly Office 365) typically use the REST protocol for Calendar operations. Exchange on-premises accounts use EWS (Exchange Web Services). Some of the shared calendar limitations documented here only affect EWS accounts, they've already been resolved for REST-based Microsoft 365 accounts. Your IT admin can tell you which protocol your account uses, or you can check under Outlook > Preferences > Accounts and look at the server details listed.
If you're running a current version and your account is Microsoft 365 with REST, and you're still hitting errors, keep reading, the step-by-step section has you covered. But for a surprising number of users, updating Outlook and confirming the account type is enough to unblock everything.
This error shows up in a very specific scenario: you have owner permissions to someone's shared calendar in Outlook for Mac, and you try to grant another person access to that calendar via the Calendar Properties dialog box. Outlook throws back "Not allowed to share this calendar." and you're stuck.
Here's the important context: this is by design. Microsoft's documentation is explicit about it. In Outlook for Mac, only the original owner of the calendar can grant permissions to other users. It doesn't matter that you have owner-level access yourself, you still can't delegate sharing rights from the Mac client. This is a difference from Outlook for Windows behavior, and it catches a lot of users off guard.
The correct resolution path is this:
- Contact the original calendar owner and ask them to grant the required permissions directly from their own Outlook account.
- If the original owner is no longer with the organization (a common scenario in enterprise environments), your Exchange or Microsoft 365 admin can assign calendar permissions via the Exchange Admin Center or PowerShell. Have your admin run:
Add-MailboxFolderPermission -Identity "user@domain.com:\Calendar" -User "newuser@domain.com" -AccessRights EditorReplace Editor with the appropriate role: Reviewer for read-only, Author for read/create, or Owner for full control. This PowerShell approach bypasses the Outlook for Mac UI limitation entirely and works regardless of whether the original calendar owner is available.
When the permissions are correctly set via admin tools or by the original owner, the person you're sharing with should be able to see the calendar in their Outlook for Mac sidebar without any further steps. If they can't see it, have them go to File > Open > Shared Calendar and enter the calendar owner's name manually.
You receive an email from a meeting attendee. It says something like "[Name] has tentatively accepted, but proposed that you change the meeting time and then send an update. Proposed new time: Thursday, 3:00 PM." You look for an "Accept Proposal" button. It's not there. The Propose New Time feature in Outlook for Mac has a gated availability that depends on both your client version and your server version.
Here's the version gate: The Propose New Time feature is available only in Outlook 2016 for Mac version 15.9 and later, and only when you're connected to Microsoft Exchange Server 2013 Service Pack 1 or a later version (including Exchange Online / Microsoft 365). Both conditions must be true simultaneously. If either one fails, the Accept Proposal and View All Proposals buttons simply don't appear in the UI.
If you're on version 15.9 or later and connected to a supported Exchange version:
- Open the New Time Proposed email message from the attendee.
- You should see either Accept Proposal or View All Proposals buttons at the top of the message.
- Click Accept Proposal to update the meeting to the suggested time and automatically send updates to all attendees.
- Click View All Proposals if multiple attendees have sent time suggestions, this gives you a consolidated view to pick from.
If you're on an older version or older Exchange Server, the workaround is manual:
- Open the meeting from your own Calendar view (not from the email).
- Change the date and time to match what the attendee proposed.
- Click Send Update to notify all attendees of the change.
It's a few extra clicks, but it achieves the same result. The attendee who proposed the new time will receive the updated invite and can accept or decline like any normal meeting.
You try to drag a meeting from your personal calendar to a shared one. Or right-click looking for a Move or Copy option. Nothing. Outlook for Mac doesn't let you do it, and this is another deliberate design choice, not a bug.
Microsoft's reasoning is actually sensible when you think about it: if you move a meeting that has attendees from one calendar to another, it creates a data consistency problem. Your local copy of the meeting diverges from what the meeting organizer and other attendees have on their end. You could easily miss updates, cancellations, or agenda changes that the organizer sends to the original meeting. So Microsoft blocks the action to protect calendar integrity.
The important distinction to know: appointments can be moved between calendars; meetings cannot. An appointment is a calendar item with no attendees, it only exists on your calendar. A meeting has attendees. If you're dealing with a solo appointment that you accidentally put on the wrong calendar, just drag it over freely.
The correct workaround for meetings is to forward the meeting to the email address associated with the target calendar:
- Open the meeting in your calendar.
- Click Forward (not Reply).
- Address the forward to the email account tied to the calendar where you want the meeting to appear.
- Send it.
- Log in to or switch to that account in Outlook for Mac, and accept the forwarded meeting invite.
Yes, it's a workaround rather than a clean drag-and-drop, but it's the officially supported approach. If you're trying to do this at scale across many meetings, it's worth asking your Exchange admin whether calendar delegation settings might better serve your workflow than manually forwarding each one.
This is the one that drives people the most crazy because it feels like a contradiction: you've been granted permission to a calendar, yet Outlook tells you "Outlook cannot open the folder. You do not have permission to open this folder. Contact [Calendar owner's name] for permission."
The root cause is almost always the same: the calendar owner shared a sub-calendar with you but forgot to also share their primary (default) Calendar folder. In Outlook for Mac, the EWS protocol requires that you have at least Reviewer permission on the default Calendar folder before you can access any of the sub-calendars beneath it. The sub-calendar permission alone is not enough.
Think of it like a filing cabinet: someone gave you a key to the second drawer, but the cabinet itself is still locked. You need both keys.
Resolution steps for the calendar owner to follow:
- In Outlook (ideally from a Windows machine where the sharing UI is more capable), right-click the top-level Calendar folder and select Properties.
- Go to the Permissions tab.
- Add the person who needs access and give them at minimum Reviewer permission.
- Do the same for the specific sub-calendar the person needs to see.
- Have the other person close and reopen Outlook for Mac, then try accessing the shared calendar again.
One key note from the official documentation: this two-folder permission requirement is specific to accounts using the EWS protocol (Exchange on-premises). If you're on a Microsoft 365 account using the REST protocol for Calendar, this issue no longer applies, Microsoft resolved it at the server level for those accounts. Check with your IT admin if you're not sure which protocol your account uses.
This one is less a blocker and more an annoyance, but if your workflow involves passing image files to another system that expects a strict .jpg extension, it can genuinely break things downstream. When you try to save an email attachment that has a .jpg file name extension in Outlook 2016 for Mac, Outlook pops up a dialog asking whether you want to keep the .jpg extension, use .jpeg, or "Use Both." Whatever option you choose, Use Both or Use .jpeg, the saved file ends up with a .jpeg extension.
This behavior applies to Outlook 2016 for Mac and is documented by Microsoft as a known behavior. The image itself is not affected, the pixel data, quality, and metadata of the JPEG image are identical either way. Only the file name extension changes. So if your concern is image quality, stop worrying. If your concern is the extension string itself, here's how to deal with it:
After saving the file with the .jpeg extension:
- Open Finder on your Mac.
- Navigate to where you saved the file.
- Click the file once to select it, then press Return to rename it.
- Change
.jpegto.jpgmanually. - Press Return again. macOS may warn you about changing the extension, click Use .jpg.
There's also a bulk workaround for the Save All scenario: when you use Save All on multiple .jpg attachments at once, the dialog doesn't appear at all, all files are saved with .jpeg automatically. If you need .jpg extensions for all of them, a quick Terminal rename command handles it cleanly:
cd ~/Downloads && for f in *.jpeg; do mv "$f" "${f%.jpeg}.jpg"; doneRun that in Terminal after saving, adjusting the path to wherever you saved the files. It renames every .jpeg in that folder to .jpg in one shot.
Advanced Troubleshooting
If the step-by-step fixes above didn't fully resolve your Outlook for Mac problems, or if you're an IT admin managing these issues across a fleet of Mac machines, this section covers the deeper scenarios.
Understanding the EWS vs REST Protocol Difference
This is the single most important thing enterprise admins can know about Outlook for Mac calendar troubleshooting. Many of the shared calendar limitations, particularly the "You do not have permission" error and some sharing permission constraints, are artifacts of the EWS (Exchange Web Services) protocol. EWS was designed for Exchange on-premises, and it has certain architectural constraints around how calendar folder permissions are checked in a hierarchy.
Microsoft has resolved several of these issues for accounts that use the REST protocol, which is the default for Microsoft 365 (formerly Office 365) cloud-hosted accounts. If your organization is still running Exchange on-premises and users are hitting these calendar access errors repeatedly, the long-term fix is migration to Exchange Online, not an easy decision, but it eliminates an entire category of Mac-specific calendar issues.
Confirming Which Protocol Your Account Uses
In Outlook for Mac, go to Outlook > Preferences > Accounts. Select your Exchange account. Look at the server type shown. If it says Exchange and lists an on-premises server address, you're on EWS. If it shows a Microsoft 365 endpoint, you're likely on REST. Your admin can also confirm this by checking the autodiscover configuration in the Exchange Admin Center.
Shared Calendar Folder Structure Requirements
One issue that comes up in environments where users have complex shared calendar setups: Outlook for Mac can only open a shared Calendar folder if it is a sub-calendar directly under the user's default Calendar folder. If a user has shared a calendar that sits at a different level in the folder hierarchy, not nested under their primary Calendar, Outlook for Mac simply cannot open it, regardless of permissions. This is an architectural limitation of the Mac client.
The only resolution is for the calendar owner to restructure their calendars so that all shared calendars are sub-folders of their default Calendar folder. Have them:
- Open Outlook on Windows or use Outlook Web App (OWA).
- Create a new calendar nested under their primary Calendar folder.
- Move events from the problematic calendar to the new correctly-nested one.
- Re-share the newly structured calendar with the appropriate people.
Checking Outlook for Mac Logs
When sharing errors occur, Outlook for Mac writes diagnostic information to its logs. You can find these at:
~/Library/Group Containers/UBF8T346G9.Office/OfficeVersionsMacOS/Open the relevant log files in Console.app or a text editor. Search for strings like "NotAllowedToShare" or "AccessDenied" to find the specific error context. This is useful when you need to provide Microsoft Support with reproduction details.
If you've confirmed your Outlook version is current, your Exchange Server is 2013 SP1 or later (or you're on Microsoft 365), permissions are correctly set on both the primary and sub-calendar folders, and you're still hitting calendar access errors, it's time to escalate. Collect your Outlook version number, Exchange Server version, protocol type (EWS or REST), and the specific error text from the logs before you call. That information will save significant time. Reach Microsoft Support directly for enterprise incidents that require server-side investigation.
Prevention & Best Practices
Most of the Outlook for Mac calendar headaches I've described in this guide are either version-dependent or configuration-dependent. That means they're largely preventable with the right habits and setup. Here's what keeps these problems from coming back.
Keep Outlook Updated on Every Mac
The version gap between Outlook 2016 for Mac 15.8.2 and 15.9 is the difference between having and not having the Propose New Time feature. That's a meaningful gap for anyone who manages a lot of meetings. Enable Microsoft AutoUpdate so Outlook stays current without anyone having to remember to check manually. Go to Help > Check for Updates, click the gear icon, and set it to Automatically Download and Install. Do this on every Mac in your environment, or push the configuration via MDM if you're managing at scale.
Structure Shared Calendars Correctly From the Start
If you know you'll need to share a calendar with someone, create it as a sub-folder of your default Calendar folder from day one. Creating it at the wrong level and then trying to share it creates a problem that can only be fixed by restructuring. Establish a naming convention, like "Team Meetings" nested under Calendar, and stick to it.
Set Permissions on Both Primary and Sub-Calendars Together
Every time you share a sub-calendar with someone, immediately also grant them Reviewer permission on your primary Calendar folder. Make it a habit, not an afterthought. The "You do not have permission" error exists almost entirely because people share the sub-calendar and forget the primary. Do both at the same time and you eliminate the error before it happens.
Educate Users on Meeting vs. Appointment Differences
The inability to move meetings between calendars surprises users who are used to Outlook for Windows. A quick 60-second explanation during onboarding, "meetings have attendees and can't be dragged between calendars on Mac, but appointments can be", prevents a lot of support tickets. Add it to your internal Outlook for Mac onboarding guide if you have one.
- Enable Microsoft AutoUpdate on all Macs so Outlook stays at the latest version automatically, especially important for the Propose New Time feature availability.
- When sharing any sub-calendar, always simultaneously share the primary Calendar folder with at least Reviewer permission to prevent access denied errors.
- If you need to save JPEG attachments with a strict .jpg extension, use the Terminal rename command after saving rather than fighting the Outlook dialog.
- For organizations on Exchange on-premises hitting repeated shared calendar issues, evaluate migration to Exchange Online (Microsoft 365), it resolves multiple Mac-specific EWS protocol limitations at the server level.
Frequently Asked Questions
Why does Outlook for Mac say "Not allowed to share this calendar" even though I have owner permissions?
This is by design in Outlook for Mac. Even if you have owner-level access to someone else's shared calendar, you cannot grant permissions to other users from the Mac client, only the original calendar owner can do that. If the original owner is unavailable or has left the organization, an Exchange or Microsoft 365 admin can use PowerShell to assign the permissions directly via the Add-MailboxFolderPermission cmdlet, which bypasses the Mac client limitation entirely. This is documented behavior, not a bug Microsoft plans to fix.
I updated Outlook for Mac to the latest version but I still can't see the Accept Proposal button, what's wrong?
The Propose New Time feature requires both conditions to be true at once: your Outlook for Mac must be version 15.9 or later, and your account must be connected to Exchange Server 2013 Service Pack 1 or a later version (including Microsoft 365). If your organization runs Exchange on-premises at an older version, Exchange 2010 or earlier, for example, the button simply won't appear no matter what version of Outlook you're running on the Mac. Check with your IT admin to find out which Exchange Server version your account connects to.
How do I move a meeting to a different calendar in Outlook for Mac?
You can't move meetings directly in Outlook for Mac, this isn't a bug, it's a deliberate design decision to prevent calendar data inconsistencies with meeting organizers and other attendees. The supported workaround is to forward the meeting to the email address associated with the target calendar account, then accept the forwarded invite from that account. Note that if what you're trying to move is an appointment (no attendees), you can drag it freely between calendars, the restriction applies specifically to meetings that have attendees.
Someone shared their calendar with me but I get "You do not have permission", why?
The most common cause is that the calendar owner shared a sub-calendar with you but didn't also share their primary (default) Calendar folder. In Outlook for Mac, the EWS protocol requires at least Reviewer permission on the top-level Calendar folder before you can access any folders nested beneath it. Ask the calendar owner to grant you Reviewer permission on their primary Calendar as well. This issue doesn't affect Microsoft 365 accounts using the REST protocol, it's specific to Exchange on-premises EWS connections.
My .jpg email attachments keep saving as .jpeg in Outlook for Mac, does this affect image quality?
No, image quality is completely unaffected. The .jpg and .jpeg file name extensions refer to the same image format, JPEG. Outlook 2016 for Mac changes the extension to .jpeg when you save, but the actual image data is byte-for-byte identical to the original. If you need strict .jpg extensions for compatibility with another system, rename the saved file in Finder or batch-rename using the Terminal command for f in *.jpeg; do mv "$f" "${f%.jpeg}.jpg"; done run in the folder where you saved the files.
Can I open a shared calendar in Outlook for Mac that isn't a sub-folder of the owner's main Calendar?
No, this is a known architectural limitation. Outlook 2016 for Mac and Outlook for Mac 2011 can only open shared Calendar folders that are nested directly under the calendar owner's default Calendar folder. If the shared calendar sits at a different level in the folder hierarchy, Outlook for Mac cannot open it regardless of your permission level. The only resolution is for the calendar owner to recreate the calendar as a proper sub-folder of their default Calendar, then re-share it and re-grant permissions. This restructuring is best done through Outlook on Windows or Outlook Web App where the folder management UI is more capable.