Strange Problem Receiving Notification Email

I just moved to a new server, and not receiving new comment email notifications anymore. I tried to disable all the plugins or send mail using SMTP, all did not work.

But if I add a new user from admin page, I can receive the email says new user registration on my blog, meanwhile the new registered user cannot receive the email even I check the “Send this password to the new user by email” option.

It’s pretty weird, seems the mail function works, but not always…

Any ideas? Thanks!