How to check if there is no incoming email?

Question

gmail

Task:
To receive letters from the list of clients. If someone from the list did not send a letter, perform the necessary action, for example, send a letter with an indication of the unsent letter in the subject line.
There is a mail domain on Google, on which I want to tie everything up. I wanted to use filters, but they work on an event, not on its absence.

I see it like this:
Scheduled service parses mail from a gmail box for the presence / absence of necessary signs.

Perhaps you can use ifttt.com for this

Answer 1

Read about contextual gadgets developers.google.com/google-apps/gmail/contextual_gadgets
Launch your own using a ready-made (or self-written) trigger, for example, comparing a given list of recipients with the current one for today and send a message to him if the recipient is absent in the list.
Google Apps also allows you to run the application on a schedule.

Answer 2

If for Linux, then in cron to start the backup, add the mail to which to send messages from the console. Accordingly, you need to start the backup with such output parameters to the console so that you can determine whether the completion was successful or not. cron will send you the log anyway.

Answer 3

Figured out how to do it with sql. If on schedule to make a request. That's just how to force to drive records into the database using mail?