Did you read the email?
When reactivating a user who lapsed for this reason, they HAVE TO login that day, or they get deactivated that night by the work flow. So when I reactivate, I always send a user explaining that they must login today, I explain why, and what will happen if they don't. The user I set up yesterday didn't follow these instructions and was upset when they were disabled today. So anyone who has not logged in for 90 days gets automatically deactivated by a nightly work flow. So my first email of the day was 'you just set me up yesterday, what gives'. My reply was basically....did you not receive my email yesterday? I can understand different ability levels, mistakes happen, etc.