Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi. I'm Brian and I'll try to help.
Outlook.com is not a platform that is suitable to mass mailing. If you want to send out messages to more than a few people at a time, it's better to use a service suited to that, like mailchimp or groups.io. Mailchimp's free plan allows you to send up to 250 recipients at a time and up to 500 messages per month. Groups.io's free plan allows 100 recipients per message.