I can send emails but am unable to receive emails on WorkMail

I have done more tests. I can send emails to multiple addresses but only receive from certain addresses. For example, when I send emails to Gmail and Microsoft, both get delivered, but when I reply from there, only the reply from Gmail is received; I can't see the reply from Microsoft.

Hi,

After adding the domain to WorkMail did you also update the user to have and email address with the custom domain? If a user was already created before the domain was added they will not automatically get an email address with the new domain.

Kind regards, Robin

Yes, the user has appropriate email address associated with the custom domain

No, I don't get any bounce or report that shows failure. I have sent emails from Yahoo and Gmail, and both were received correctly.

I can send emails from my Microsoft account, and they are received by others.