Add "batch resend" feature for failed messages within a time range.
Why this is an important feature:
If you've used a shared IP and use the mailgun API to send customer receipts, order confirmations etc, and the IP has been flagged for spam or blocked, you then purchase a dedicated IP, and now you need to resend the failed messages, today you have to do this manually, and if you have several hundred or thousands of messages, this is a extremely big waste of time.
Helge Sverre Hessevik Liseth commented
Sorry the title was broken it should say "Batch Resend"