Configurable new user time on "Temporary interaction limits > Limit to existing users"

[cirosantilli]

Currently, when you set "Limit to existing users", it prevents users with accounts newer than 24 hours from interacting.

I would like to increase the 24 hour hour limit to a larger custom time, e.g. one week.

Motivation is same as ;#1901 to fight users who spam by creating/deleting accounts repeatedly.