Organizing and accessing contact information in Outlook.com
Hello Judith, don't worry this thread won't be closed until 48 hours after your last response, or if you close it yourself. And I can't see the email address that you have shared because they are removed automatically since this is a public forum and it is not recommended for you to share private information.
Now since it is working now without any issues then I am assuming that you were having this issue because of the people that were no longer working with you. I am assuming that their accounts are closed now and it is the reason that your emails were not going through.
The limit is way above 250 people, so the issue could have been because of the old email addresses.
Looking forward to hearing from you.
Mustafa