Nginx connection close module

Hello,

I’m sending you this email after some hours of struggling on google and
nginx related page/articles/wiki for finding some nginx plugin for tcp
disconnect/reset of some client.

My plan is to make an reverse mail (imap/pop3) proxy using nginx. I need
an
nginx module to close/terminate an particular client connection in cases
of
for example the account password was changed. MUAs like
thunderbird/outlook
tend to keep some persistent connections with the server (5 by default).

Now, the question is: do you know any module for nginx witch could help
me
implement such thing?

Thank you in advance,
Mike.