Disable mail notification to a specific user

[vaidy]

Hi
We use Mantis Bugtracker 1.1.8 on Windows.
It is configured to send mail alerts to all managers for any action taken on a bug.
But for one of the managers i've disabled all mail alerts. Even then there are one or two alerts being sent to this user. Is there any other place to check & disable the alert for this specific user. I've made sure that this user has not opted for monitoring of any bug.
Regards
Vaidy