When using Website X5 professional, user can register to access an area using automatic registration. It is important to offer an unsubscribe link. How can a user unsubscribe automatically?

I looked at the database file and I am concerned that the passwords are readable in plain text. This needs to be changed to secure the passwords as otherwise it is a MASSIVE security risk.

I need the ability to automatically send emails to the users, based on when they joined.

e.g. the first email one day after joining, the second two days after joining, etc.

I can write a script to do this, but are the database entries persistent or are they downloaded once they are downloaded to the software with the update button?