portal.cires.pt is using external name servers and does not have any MX records set for it. Without MX records, other mail servers have no way to know where to deliver mail sent to your domain.
You will need to create the MX records via your current NS provider. The values you will need are available in our documentation: What are your MX servers?
Also, unrelated to the problem but I noticed that you're using "imap1.de.opalstack.com" as your incoming mail server. Please change that to "mail.de.opalstack.com". Complete client configuration details are in our docs: Email Client Configuration