UPDATE: New Microsoft Online Services Modules. You now need to download the Logonassistant before you can install the Module.

More than once, I’ve encountered the situation, where a client of mine, had to send out somewhere between 10.000 and 12.000 e-mails at once. It’s not like a newsletter, but just something that they needed once for a huge event. I’ve found that Office 365 Distribution Groups can really be a useful and free tool.

You will need to send this e-mail through a distribution group. Otherwise, you will be pretty sure that you will reach the 1500 mail a day limit that Office 365 has pretty fast, if you try to use Outlook. Don’t panic, it’s a normal restriction. Most other Exchange hosts have it. With Office 365 Distribution Groups, you can add up to 100.000 members, that will receive your brilliant wisdom. You just need to follow my simple directions and you will be sending words of knowledge to a ton of people in no-time.

Enter PowerShell

I’ve made a PowerShell Script that can make a distribution group that’s capable of sending all those e-mails, through a single e-mail address. Usually when you have a big distribution group like that, you don’t want everyone to be able to send e-mails to everyone. You can have that. I’ve disabled that in my script, but you can always change that in the Portal, later on.

If you don’t want to approve the e-mail, before it’s finally sent to the group, go into the portal – Exchange admin – Distribution groups, and edit the group. Here you can put your own name in the section where users, that are able to send e-mails to the group without approval, is put.

How to create the Distribution Group in Office 365:

  1. Download and install the Microsoft Online Services Logonassistant
  2. Download and install one of the two PowerShell modules (depending whether you are running a 32 or 64 bit machine)
  3. Edit the PowerShell Script you download from the link below
  4. Generate a csv-file (But use my demo first as a test, to see if the connection is working)
  5. Open the “Microsoft Online Services Module for Windows PowerShell” and execute this command
    • Set-ExecutionPolicy unrestricted (It will allow you to run the script)
  6. Run the script
  7. Get coffee. For 10.000 users, it can take up to a couple of hours for it to finish in my experience.


Download PowerShell Script and CSV-file
Go ahead and download the zip-file. It contains a PowerShell Script and a demo csv-file.With this you can create distribution groups and add up to 100.000 members in one simple step.

If you have any problems using the script, have suggestions on how to improve it or just want to boost my ego by complementing my work, feel free to drop me a comment below.

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