daily batch task, what are my options to optimize or automate?

[Xtrafresh]

We use roundcube to monitor a rather active outgoing stream of traffic, generated by several customers. All above board, by the way

Every day, we go through several folders for each customer, and set all the unread mails to read. The problem is that now that we are getting more customers, this is taking more and more time, and it seems like a good candidate for a task that can be optimized or automated. so, here's my question:
What are my options to do batch status changes to all emails in all subfolders of a certain parent folder?

[alec]

The "Mark al as read" action in folders menu has "Selected folder and its subfolders" option.

[Xtrafresh]

That is EXACTLY what I need, but I can't find the button for the life of me. 

Could you help me out with a screenshot? we're using roundcube 1.0.1 if that makes a difference.

[alec]

1.0 is very old, you need something newer.