The mail was only sent to serveral people

Hi, everyone.

I met a strange problem:
The gitlab only send mail to me and one of my colleague (We two deployed gitlab).

The “only send to me and one of my colleague” means that no matter in which project (and no matter if we are in these projects) and no matter who push code and no matter how we set the notify setting, it sent mail and only sent mail to us.

I guess it maybe is a problem about web hook or any else about configuration. But when I searched configuration files(even the whole directory which the gitlab is in), I can’t find any about me or my colleague.

Is there any similary problem? Or some suggestions about how to solve or how to find the direct problem?

Thank you.