Hi there,

On my website (joomla 3.x, K2 and T3), I want that if I block a user for 3 months (or 1 year or permanently), so a notification will appear on his devices' screen, for example "You have been blocked because of spamming. See you in 3 months (or 1 year or infinity)" rather than the system message "Warning - Login denied! Your account has either been blocked or you have not activated it yet."

The second is after 3 months, I want the above account will be automatically (or manually) unblocked. And an email with unblocking notification will be sent to his email.

Of course I also want to manage a number of blocked users at the same time.

Is there any possible idea, any plugin or module to manage this action for above things? Thanks in advance.

Can anybody kindly help me?

Perhaps you can try Joomla Community Builder - extensions.joomla.org/extensions/extension/clients-a-communities/communities/community-builder

Actually this is not directly related to K2.
You need to look for an extension with this functionality in the JED.