[Dovecot] OT: Counting emails in IMAP folders

[Nigel Allen]

Greetings

I have a customer who has mail server running dovecot with an IMAP 
account (Customers) which contains hundreds of folders (one per customer).

Looks like this:

Customers
    Fred Smith and Co
    Joe Blogss
    Cust-1
    Cust-n
   

They have a requirement to report monthly on the total number of emails 
added to each customers' folder during the month.

Basically I need to be able to run some kind of command line query that 
will give me each of the sub-folder names and the number of emails added 
to the folder for that month (or other user-specified time period).

Any ideas please?

TIA

Nigel.