Aaaah, I getcha. thats a good point and yes, i get those kinds of clients too. Sometimes they are a little busy and forget to report it back that there's still an issue but sometimes it's a little problem and they aren't too worried about it.
The problem is flagging the jobs that are older than 7 days after you have emailed them otherwise it'll keep emailing them 8 days,9 days,10,11 etc. There must be a flag in the table like a 'followup' flag or something.
if you're happy to alter your ticket table then I can implement something like this for you.
I usually do some quick patches to make things work but have some small hardcoded code to minimise changes otherwise we'd be tweaking alot of the configuration pages of osticket which I'm reluctant to do since upgrading it would break the changes we've applied....
if others think this patch is worth it, i'll consider adding it in as i'm already working on other customizations.