Compare Outlook add-in support in Outlook on Mac with other Outlook clients

You can create and run an Outlook add-in the same way in Outlook on Mac as in the other clients, including Outlook on the web, Windows (new and classic), iOS, and Android, without customizing the JavaScript for each client. The same calls from the add-in to the Office JavaScript API generally work the same way, except for the areas described in the following table.

For more information, see Deploy and install Outlook add-ins for testing.

Area	Outlook on the web, Windows (new and classic), and mobile devices	Outlook on Mac
Supported versions of office.js	All APIs in Office.js.	All APIs in Office.js. NOTE: In Outlook on Mac, only Version 16.35 (20030802) or later supports saving a meeting. Otherwise, the saveAsync method fails when called from a meeting in compose mode. See Cannot save a meeting as a draft in Outlook for Mac by using Office JS API for a workaround.
Instances of a recurring appointment series	Can get the item ID and other properties of a master appointment or appointment instance of a recurring series. Can use mailbox.displayAppointmentForm to display an instance or the master of a recurring series.	Can get the item ID and other properties of the master appointment, but not those of an instance of a recurring series. Can display the master appointment of a recurring series. Without the item ID, cannot display an instance of a recurring series.
Recipient type of an appointment attendee	Can use EmailAddressDetails.recipientType to identify the recipient type of an attendee.	EmailAddressDetails.recipientType returns undefined for appointment attendees.
Version string of the client application	The format of the version string returned by diagnostics.hostVersion depends on the Outlook client. Outlook on Windows: Returns the version of the Outlook client. For example, 16.0.4454.1002. Outlook on the web and new Outlook on Windows: Returns the version of the Exchange Server. For example, 15.0.918.2	The diagnostics.hostVersion call returns the version of the Outlook client. For example, 16.0 (140325).
Custom properties of an item	If the network goes down, an add-in can still access cached custom properties.	Because Outlook on Mac does not cache custom properties, if the network goes down, add-ins would not be able to access them.
Attachment details	The content type and attachment names in an AttachmentDetails object depend on the type of client: A JSON example of AttachmentDetails.contentType: "contentType": "image/x-png". AttachmentDetails.name does not contain any filename extension. As an example, if the attachment is a message that has the subject "RE: Summer activity", the JSON object that represents the attachment name would be "name": "RE: Summer activity".	A JSON example of AttachmentDetails.contentType: "contentType" "image/png" AttachmentDetails.name always includes a filename extension. Attachments that are mail items have a .eml extension, and appointments have a .ics extension. As an example, if an attachment is an email with the subject "RE: Summer activity", the JSON object that represents the attachment name would be "name": "RE: Summer activity.eml". NOTE: If a file is programmatically attached (e.g through an add-in) without an extension then the AttachmentDetails.name will not contain the extension as part of filename.
String representing the time zone in the dateTimeCreated and dateTimeModified properties	As an example: Thu Mar 13 2014 14:09:11 GMT+0800 (China Standard Time)	As an example: Thu Mar 13 2014 14:09:11 GMT+0800 (CST)
Time accuracy of dateTimeCreated and dateTimeModified	If an add-in uses the following code, the accuracy is up to a millisecond. JSON.stringify(Office.context.mailbox.item, null, 4);	The accuracy is up to only a second.

Add-in support in Outlook on new Mac UI

Outlook add-ins are now supported in the new Mac UI (available from Outlook version 16.38.506). For requirement sets currently supported in the new Mac UI, see Outlook API requirement set client support.

To learn more about the new Mac UI, see The new Outlook for Mac.

You can determine which UI version you're on, as follows:

Classic UI

New UI

Support for add-ins with the unified manifest for Microsoft 365

Add-ins that use the unified manifest for Microsoft 365 aren't directly supported in Outlook on Mac. To run this type of add-in, it must first be published to AppSource. An add-in only manifest is then generated from the unified manifest, which enables the add-in to be installed in Outlook on Mac.

If you're deploying an add-in that uses the unified manifest in the Microsoft 365 Admin Center and require it to run in Outlook on Mac, the add-in must be a published AppSource add-in. Custom add-ins or line-of-business (LOB) add-ins that use the unified manifest can't currently be deployed in the Microsoft 365 Admin Center.

For more information, see the "Client and platform support" section of Office Add-ins with the unified app manifest for Microsoft 365.