Combine daily digest emails from different forums into one?

[Trillian]

Our message board is set up so there are 10 forums to help categorize the different topics we discuss. There is potential for more categories therefore more forums.

Users would like to receive a daily digest of all the message board activity. In order to do that they need to individually subscribe to each forum. Understood.

However, when you subscribe to 10 forums, that means potentially you receive 10 daily digest emails a day... one for each forum.

We would like to reduce this amount of email. So I am considering two options and open to others:

1. Reformat the message board, but how? We still want to keep our categories, but somehow have them under a single forum so there is one daily digest email, is that possible? Or,

2. Programmatically create a single daily digest email of all the forums. I am guessing this can be done in /forum/includes/functions_digest.php script, but I'm unsure how to proceed. The use of prepared statements for the MySQL queries requires some research and learning (not complaining, just that I don't want to screw things up!) and overall the coding is tricky for me to follow. Still, it seems the solution is in this script somehow.

Any advice? Or other solutions? Your attention is appreciated on this