Github user sebbASF commented on the issue:
https://github.com/apache/incubator-ponymail/issues/420
Huh? they don't sort correctly on my system:
$ ls -1 dev_po*.mbox
dev_ponymail_apache_org_2017-1.mbox
dev_ponymail_apache_org_2017-11.mbox
dev_ponymail_apache_org_2017-12.mbox
dev_ponymail_apache_org_2017-2.mbox
I agree the month should be padded with a leading 0 if required.
This could be done in the GUI, but I think it's better done in the backend.---
