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Outlook client and server API compatibility of the Phishing Report Button

The Outlook add-in makes use of Exchange Web Services (EWS) or the Outlook REST API, in order to retrieve data from the user's Outlook mailbox.

Below you can find the availability of the EWS and REST API for all supported Exchange Server / Outlook client combinations and their impact on forwarding.

The REST API is the newer interface and offers more possibilities in comparison to EWS. The limitations of using EWS are listed later in the article.

Exchange On-Premises

For all Exchange On-Premises servers (no hybrid deployment) we can only support EWS.

Exchange Online/Hybrid Server Deployments

For Exchange Online and hybrid deployments of Exchange Servers, the following client/server combinations for EWS, Graph API and REST API are available:

REST: REST API only
EWS: EWS only
Graph: Graph API only
All: EWS + Rest API + Graph API

 

Windows

Windows

Windows Outlook clients

MS 3651

Outlook 2021

Outlook 2019

Outlook 2016

Outlook 2013

Server

Exchange Online

All

All

All - Graph MSAL PopUp

EWS

EWS

Exchange 20192

All

All

All- Graph MSAL PopUp

EWS

EWS

Exchange 20162

EWS/ REST

EWS/ REST

EWS/ REST

EWS

EWS

Exchange On-Premise

EWS

EWS

EWS

EWS

EWS

 macOS

macOS

macOS Outlook clients

Office on Mac (classic UI)

Office on Mac (new UI)

Server

Exchange Online

All

All

Exchange 20192

All

All

Exchange 20162

EWS/REST

EWS/REST

Exchange On-Premise

EWS

EWS

Other 

Other

Outlook clients

Android App

iOS App

Web Browser (Exchange Online)

Web Browser (On-Premise)

Mobile Browser

Server

Exchange Online

Graph/ REST

Graph/ REST

All

EWS/REST

not supported

Exchange 20192

Graph/ REST

Graph/ REST

All

EWS/REST

not supported

Exchange 20162

REST

REST

EWS/REST

EWS/REST

not supported

Exchange On-Premise

not supported

not supported

n/a

EWS/REST

not supported

Microsoft Office 365 subscription
connected to Exchange Online (hybrid deployment)

Graph MSAL PopUp: Every time a user opens the Phishing Report Button, the user will see a flash of a MSAL pop-up for logging in the user via Graph

Outlook client and server API compatibility of PhishAssist

Operating system

Office version

Edge WebView2 (Chromium-based) installed?

PhishAssist

Android

Any

Not applicable

Yes

Any

Office web

Not applicable

Yes, if not opened on IE11

iOS

Any

Not applicable

Yes, if not opened on IE11

Mac

Any

Not applicable

Yes

Windows 7, 8.1, 10, 11

Non-subscription Office 2013 to Office 2019

Does not matter

Not supported

Windows 10, 11

Non-subscription Office 2021 or later

Yes

Yes

Windows 7

Microsoft 365

Does not matter

Not supported

Windows 8.1, Windows 10 ver. < 1903

Microsoft 365

No

Not supported

Windows 10 ver. >= 1903, Windows 11

Microsoft 365 ver. < 16.0.11629

Does not matter

Not supported

Windows 10 ver. >= 1903, Windows 11

Microsoft 365 ver. >= 16.0.11629 and < 16.0.13530.204242

Does not matter

Yes

Windows 10 ver. >= 1903, Windows 11

Microsoft 365 ver. >= 16.0.13530.204242

No

Yes

Windows 8.1, 10, 11

Microsoft 365 ver. >= 16.0.13530.204242

Yes

Yes

Note: This table includes information on the compatibility of PhishAssist with different operating systems, office version, and whether Edge WebView2 (Chromium-based) is installed. The entries "Not applicable" and "Does not matter" indicate that a particular criterion is not relevant to a specific combination of operating system and office version.
 

Differences in forwarding via EWS and REST/Graph API

Forwarding can be done in “.eml” or “split” mode. Depending on the available API and the configured forwarding mode, the following files are forwarded to the customer’s email addresses:

 

 

via Rest / Graph 

via EWS

.eml mode

  • mail.eml

  • mail.eml

    • for emails greater than 500kB the add-in automatically switches to split mode

Split mode

  • body.html

  • header.text

  •  All attachments as the original files³

  • body.html

  • headers.txt

  • attachments.txt³

    •  contains information about the attachment`s name, size, type, isInline

3 If the email contains attachments

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