How can I notify Linux administrator that the OS-level password is due to expire soon by email or message?

Hello:  I am new to Linux and don't have a Linux system to work on.  I have a database background (user, planner, DBA, etc.) but no hand-on Linux experience or training in Linux administration.

I am working with a customer who regularly lets their OS-level passwords on their Linux servers expire.  They don't log in very often, so when they do, they find that the password has expired and they can't remember the old password to reset it.  

They then have to engage my company's customer service staff, who are getting a bit vexed by having to do custom work for which they previously didn't charge any money.  (For this frequent offender, they are changing that policy.)  

This also happens when our customer service staff is preparing to do service work at the Linux level and ask the customer for the password, only to find that the customer hasn't a clue.

My question is:  Will the solution given in this string of postings work for the OS level password, or only for user passwords?

If not, is there a similar solution that will?

Thank you for any assistance you might be able to give me on this question.