Can't receive emails but I can send them?

Can't receive emails but I can send them?

Nobody can reply or send my email addresses (custom domain) but I can send emails to anyone. The only way I've been able to receive emails is if I send an email from my own domain to another email that ends in my same domain but I can't send it an email from my personal email. Does anyone know what I'm doing wrong in the settings and mappings ?