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

Export calendar Items to a CSV file using Microsoft Graph and Powershell

For the last couple of years the most constantly popular post by number of views on this blog has been  Export calendar Items to a CSV file using EWS and Powershell closely followed by the contact exports scripts. It goes to show this is just a perennial issue that exists around Mail servers, I think the first VBS script I wrote to do this type of thing was late 90's against Exchange 5.5 using cdo 1.2. Now it's 2020 and if your running Office365 you should really be using the Microsoft Graph API to do this. So what I've done is create a PowerShell Module (and I made it a one file script for those that are more comfortable with that format) that's a port of the EWS script above that is so popular. This script uses the ADAL library for Modern Authentication (which if you grab the library from the PowerShell gallery will come down with the module). Most EWS properties map one to one with the Graph and the Graph actually provides better information on recurrences then...
Read more

Downloading a shared file from Onedrive for business using Powershell

I thought I'd quickly share this script I came up with to download a file that was shared using One Drive for Business (which is SharePoint under the covers) with Powershell. The following script takes a OneDrive for business URL which would look like https://mydom-my.sharepoint.com/personal/gscales_domain_com/Documents/Email%20attachments/filename.txt This script is pretty simple it uses the SharePoint CSOM (Client side object Model) which it loads in the first line. It uses the URI object to separate the host and relative URL which the CSOM requires and also the SharePointOnlineCredentials object to handle the Office365 SharePoint online authentication. The following script is a function that take the OneDrive URL, Credentials for Office365 and path you want to download the file to and downloads the file. eg to run the script you would use something like ./spdownload.ps1 ' https://mydom-my.sharepoint.com/personal/gscales_domain_com/Documents/Email%20attachments/filen...
Read more

Sending a MimeMessage via the Microsoft Graph using the Graph SDK, MimeKit and MSAL

One of the new features added to the Microsoft Graph recently was the ability to create and send Mime Messages (you have been able to get Message as Mime for a while). This is useful in a number of different scenarios especially when trying to create a Message with inline Images which has historically been hard to do with both the Graph and EWS (if you don't use MIME). It also opens up using SMIME for encryption and a more easy migration path for sending using SMTP in some apps. MimeKit is a great open source library for parsing and creating MIME messages so it offers a really easy solution for tackling this issue. The current documentation on Send message via MIME lacks any real sample so I've put together a quick console app that use MSAL, MIME kit and the Graph SDK to send a Message via MIME. As the current Graph SDK also doesn't support sending via MIME either there is a workaround for this in the future my guess is this will be supported.
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.