i dont know what happen exactly but one of my admins send an email from email1[AT]domain[dot]com that used for a department to email2[At]doman[dot]com that used for another department ( for test)
then this department emails begin to send emails to each other and everything go wrong.
i unistall module and install it again but still when i click on modules/xhelp/checkemail.php the email sending begin
it also create 2 users for email1 and email2.
i delete them but the system create them again.
now i think this is really a big problem. what happen when someone send email from one department to another for annoying?
now the sending emails stoped and i have this notices when i click on modules/xhelp/checkemail.php :

my problem solve but still i think must prevent emails from one department to another.

You were stuck in a mail loop, where one automated process responds to another automated process. They will continue to respond back and forth.

It was never our intention to have 1 department's mail account to send email to another department's mail account. I can't think of a legitimate reason that would happen.

i have a trick about this:
i have a "ban user group" and this group dont permission to access in whole site. so i send that email1 and email2 users to that group and theu dont have permission to xhelp. now is this enough for prevent that? i dont want try again

no I think that would fail to prevent this problem from happening again. I have added a bug to the xhelp bug tracker so that we can keep track of the problem better.