To collect your emails via a mail client (Outlook, Outlook Express, etc) you will need the following details:-

Incoming (POP3) Server: mail.yourdomain.com (where 'yourdomain.com' is your domain)

Outgoing (SMTP) Server: mail.yourdomain.com (where 'yourdomain.com' is your domain)
You can send mail through the SMTP server shown above provided your mail client supports SMTP authentication, authenticate with your mailbox username and password.

Username: Your full email address

Password: The password you chose when creating the mailbox in Helm