There are a few ways to see all the sent emails for the last month. This can be helpful for organizations that split email marketing between departments.
Export Campaign Metrics
Go to Reporting > Export Data to export Campaign Metrics. This export will give Campaign name, Subscriber list total, and top level stats for all your email campaigns. Learn how to export Campaign Metrics.
Compare Campaigns for last month
Go to Reporting > Compare Campaigns to run a comparison report. Select Campaign type ‘Standard’ or 'Triggered', skip selecting a Label, and toggle Sent within to ‘past month’. Then select Show Results.
View Sent Campaigns for past month
Go to Reporting > Sent Campaigns. Toggle the Date dropdown to ‘Past Month’.