Help please. Contacts have been deleted from my DLs purposefully but they are still getting my group emails when they shouldn’t be.

I help manage a group distribution list and emails on an outlook account we set up for managing volunteers on a rota and other bits.

I recently deleted some volunteer emails (few weeks back now) from the main distribution list created. Whenever I send out emails to the current DL, these recipients are still getting the emails. Even though they visibly do not show or exist in the Dist list. I have even opened up the DL in the 'to' box to double check their emails don't exist, and they don't. But when my emails are sent, they still appear in the list of recipients. This is most frustrating not only for us as an admin team but also for the recipients. It's also a pain as the only other way is to select each individual and we have over 60 volunteers on our list.

Also want to prevent confidential information getting to volunteers who are no longer with the organisation.

Please can someone advise if they have experienced the same and how they managed to clear the problem.

I'm beginning to think it's a bug in MS Outlook but don't know where to file this as a fault.

Any advice welcome.

Thanks

Fe