Since PPs expire every 10 years there are 12 months/year, they would have to notify (approx.) 1.3 million/month pax. This shouldn't be a difficult programming operation.
[Most of my CCs have just send mass emailings re privacy issues...]
Many people dread additional contact from los federales,
Personally, I don’t want government email more than minimally required, and a passport expiration email would be just more junk as far as I am concerned.