I can't see both alias emails in mail on MacBook

Hi, I have two alias icloud emails, both of which I use - I have just removed an old gmail email from my macbook mail app and now I am also unable to see both icloud alias emails - can anyone help me please? I am able to switch between both to send emails but emails are only coming in for one of them - I am guessing there is a box I need to tick somewhere but I seem to be going round in circles! Thank you