It would be a really nice feature if we could have a module that we could display our latest mailing or say last 2,3, 4 mailings. The only way we can display newsletters is by a menu item which has little or no control over what is displayed.
Unfortunately this feature has not been added yet. If you like you can post it as a feature request (https://www.acymailing.com/feature-requests/). You might want to check if there's already a request for this and upvote that one.