Skip to main content

Sending a Message with a Large attachment using the Microsoft Graph and Powershell

Sending a message with a large attachment used to be the least worst option when it came to shipping data between people. In the Modern workplace where document and file sharing options are a lot better sending email with a large attachment can tends now to be the worst option especially when it comes to version control, expiration etc. However if you do find yourself with the need to send an email with large attachments (larger then 4MB) and you want to make use of the Microsft Graph API then it requires you use a different method from just sending the message in one post eg https://docs.microsoft.com/en-us/graph/outlook-large-attachments?tabs=http

This does make sending a Message a lot more complex eg if you have a Message less the 4MB you can just make one REST Post to send that message. If you have a large attachment you then have a multi step process eg

  1. Create a Draft message where you set all the other message property eg Subject,To,Body
  2. Take the MessageId(graph item id) returned in Step 1 and Create an Upload Session
  3. Read the attachment and upload the attachment in chunks until you have uploaded the entire file
  4. Send the Draft Message
Eg this is what it looks like in term of REST requests


I've put together a Powershell sample and posted it on GitHub  https://github.com/gscales/Powershell-Scripts/blob/master/Graph101/SendMessageWithLargeAttachment.ps1 that performs the above to run this use something like

Invoke-SendMessageWithLargeAttachment -MailboxName gscales@....com -filePath "C:\temp\rates.pdf" -verbose -uploadChunkSize 400000 -Subject "Test Message 1234" -body "Rgds Glen" -To glenscales@yahoo.com

The chunk size you use is up to you a larger chunk size will generally mean a faster upload but if the Network is more unreliable a smaller chunk is better




Popular posts from this blog

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 Gr...
Read more

Exporting and Uploading Mailbox Items using Exchange Web Services using the new ExportItems and UploadItems operations in Exchange 2010 SP1

Two new EWS Operations ExportItems and UploadItems where introduced in Exchange 2010 SP1 that allowed you to do a number of useful things that where previously not possible using Exchange Web Services. Any object that Exchange stores is basically a collection of properties for example a message object is a collection of Message properties, Recipient properties and Attachment properties with a few meta properties that describe the underlying storage thrown in. Normally when using EWS you can access these properties in a number of a ways eg one example is using the strongly type objects such as emailmessage that presents the underlying properties in an intuitive way that's easy to use. Another way is using Extended Properties to access the underlying properties directly. However previously in EWS there was no method to access every property of a message hence there is no way to export or import an item and maintain full fidelity of every property on that item (you could export the...
Read more

EWS Create Mailbox folder Powershell module for Exchange and Office365 Mailboxes

This is a rollup post for a couple of scripts I've posted in the past for creating folders using EWS in an Exchange OnPremise or Exchange online Cloud mailbox. It can do the following Create a Folder in the Root of the Mailbox Create-Folder -Mailboxname mailbox@domain.com -NewFolderName test Create a Folder as a SubFolder of the Inbox Create-Folder -Mailboxname mailbox@domain.com -NewFolderName test -ParentFolder '\Inbox' Create a Folder as a SubFolder of the Inbox using EWS Impersonation Create-Folder -Mailboxname mailbox@domain.com -NewFolderName test -ParentFolder '\Inbox' -useImpersonation Create a new Contacts Folder as a SubFolder of the Mailboxes Contacts Folder Create-Folder -Mailboxname mailbox@domain.com -NewFolderName test -ParentFolder '\Contacts' -FolderClass IPF.Contact Create a new Calendar Folder as a SubFolder of the Mailboxes Calendar Folder Create-Folder -Mailboxname mailbox@domain.com -NewFolderName test -Parent...
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.