Skip to main content

Using the Tag for external email messages received feature in the Microsoft Graph and Exchange Web Services

The "Tag for external email messages received" feature was introduced into Office365 recently to help people better to identify mail that comes from external sender vs internal sender see this for more info on this feature .

What happens when you enable this feature is that for messages with External sender a new Mapi property is set on those messages eg


For messages from internal senders the property doesn't appear to get set and if the feature isn't enabled in your tenant then you won't see this property either. You can negate the boolean value of the property which will turn off the external tag.

Using it in the Microsoft Graph API


If you want to use it in the Microsoft Graph API when you retrieve messages you can include this as a SingleValueExtendedProperties eg for Retrieving and filtering message you can use


I've included this in my Get LastEmail 101 graph sample if you want to try this in a real mailbox eg you can do

 Get-LastEmail -InternalSender -MailboxName gscales@mailbox.com 

Will get the Last mail from an Internal Sender

 Get-LastEmail -ExternalSender -MailboxName gscales@mailbox.com 

Will get the Last mail from an External Sender

and you can use the -Focused or -Other switch to get the above email from the Focused or Other Inbox

Using it in Exchange Web Services


In EWS you can use a SearchFilter eg

This property is set-able so if you have an application where email is marked as external and you can't or don't want to whitelist the domain (so they no longer are marked external) you could modify this property value (on each applicable message) so they will no-longer be tagged as External for the user.
Labels:

Popular posts from this blog

Testing and Sending email via SMTP using Opportunistic TLS and oAuth in Office365 with PowerShell

As well as EWS and Remote PowerShell (RPS) other mail protocols POP3, IMAP and SMTP have had OAuth authentication enabled in Exchange Online (Official announcement here ). A while ago I created  this script that used Opportunistic TLS to perform a Telnet style test against a SMTP server using SMTP AUTH. Now that oAuth authentication has been enabled in office365 I've updated this script to be able to use oAuth instead of SMTP Auth to test against Office365. I've also included a function to actually send a Message. Token Acquisition  To Send a Mail using oAuth you first need to get an Access token from Azure AD there are plenty of ways of doing this in PowerShell. You could use a library like MSAL or ADAL (just google your favoured method) or use a library less approach which I've included with this script . Whatever way you do this you need to make sure that your application registration  https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-
Read more

The MailboxConcurrency limit and using Batching in the Microsoft Graph API

If your getting an error such as Application is over its MailboxConcurrency limit while using the Microsoft Graph API this post may help you understand why. Background   The Mailbox  concurrency limit when your using the Graph API is 4 as per https://docs.microsoft.com/en-us/graph/throttling#outlook-service-limits . This is evaluated for each app ID and mailbox combination so this means you can have different apps running under the same credentials and the poor behavior of one won't cause the other to be throttled. If you compared that to EWS you could have up to 27 concurrent connections but they are shared across all apps on a first come first served basis. Batching Batching in the Graph API is a way of combining multiple requests into a single HTTP request. Batching in the Exchange Mail API's EWS and MAPI has been around for a long time and its common, for email Apps to process large numbers of smaller items for a variety of reasons.  Batching in the Graph is limited to a m
Read more

How to test SMTP using Opportunistic TLS with Powershell and grab the public certificate a SMTP server is using

Most email services these day employ Opportunistic TLS when trying to send Messages which means that wherever possible the Messages will be encrypted rather then the plain text legacy of SMTP.  This method was defined in RFC 3207 "SMTP Service Extension for Secure SMTP over Transport Layer Security" and  there's a quite a good explanation of Opportunistic TLS on Wikipedia  https://en.wikipedia.org/wiki/Opportunistic_TLS .  This is used for both Server to Server (eg MTA to MTA) and Client to server (Eg a Message client like Outlook which acts as a MSA) the later being generally Authenticated. Basically it allows you to have a normal plain text SMTP conversation that is then upgraded to TLS using the STARTTLS verb. Not all servers will support this verb so if its not supported then a message is just sent as Plain text. TLS relies on PKI certificates and the administrative issue s that come around certificate management like expired certificates which is why I wrote th
Read more
All sample scripts and source code is provided by for illustrative purposes only. All examples are untested in different environments and therefore, I cannot guarantee or imply reliability, serviceability, or function of these programs.

All code contained herein is provided to you "AS IS" without any warranties of any kind. The implied warranties of non-infringement, merchantability and fitness for a particular purpose are expressly disclaimed.