Server does not receive emails

I updated my VPS for WHM 56.21 and now he does not receive any mail. Shipping is still correct but does not receive. I tried to send a test email through another server and the log shows this error: SMTP>> STARTTLS SMTP<< 220 TLS go ahead LOG: MAIN [23.89.x.x] SSL verify error: depth=0 error=self signed certificate cert=/CN=server.domain.com.br/emailAddress=ssl@server.domain.com.br LOG: MAIN [23.89.x.x] SSL verify error: certificate name mismatch: "/CN=server.domain.com.br/emailAddress=ssl@server.domain.com.br" And now what do I do? I need help because my server is not receiving any email.