registration email problem

Hello,  
I have been testing community builder's features in the past couple of weeks, and I just realized that I am having a registration email problem.
A new user registration does not receive an activation email.  I mean I don't receive the activation email after I successfully register.  The new user was added to the user table, and in state not confirmed.  I tried to resend confirmation email through the user management page by selecting that new user and clicked Resend Confirmation, and I never received the email.

So I built a new test site with barebone minimum extensions an hour ago:  Joomla 4.2.8, Gantry 5 Helium Theme, and Community Builder 2.8.0+build.2023.02.22.18.31.13.558d8da99.   Just want to test with everything fresh from the beginning.
I've tried several configurations:
1) Joomla user regisration is disabled, and CB user registration set to Yes, Independent CMS allow registration.
2) Joomla user registration is enabled, and CB user registration set to Yes, Independent CMS allow registration.
3) CB user registration set to Same as CMS allow registration, and Joomla user registration is enabled.
I don't get the activation email in these 3 settings.
I do receive the test email from Joomla Global Configuration : Send test mail.
Again, I tried to Resend Confirmation email through the user management page, and still no luck.
I am not using the moderation features, so there is no moderator role in my setting.  New user should be automatically approved when he/she clicked that activation link in the email, but that email never came.
I have not added any new CB fields since it is a brand new test site, so there are only standard name, username, email and password fields.
I just want to have a simple user registration system that would send an activation email after a user successfully fill out the registration page.  

Did I miss or accidentally trip any of the critical configuration/setting that would prevent the system from sending an activation email ??
Any help / hints will be appreciated.
If there is any additional info needed from me that would help to pin point to the root cause of the problem, please let me know.

Thanks in advance.

Will.

 

Apparently I can no longer use PHP mail.  Not sure why.  It worked a couple of weeks ago when I started evaluating Joomla 4, Community Builder and other extensions.  It could be that the Joomla update plug in had been sending 4.2.9 update every few hours on my several test sites, and caused my hosting company to block my PHP mail.  
So I changed it to SMTP and now it is working.  
Please accept my apology for raising a newbie type of issue. Well... I am newbie.