To setup outgoing email using a service provider that isn't Gmail or Office 365 navigate to Settings > My Details > Setup Incoming and Outgoing Email > Other, then enter your SMTP details. If you are unsure of these credentials, your service provider will be able to advise what these settings are.
This email address doesn't have to be the same one you use to login, and more than one staff user can send emails using the same email address.
To set up incoming email you will then need to login to your email admin account and set up a catch all forwarding rule to send a copy of all emails you receive to your AccountancyManager account. You will find you forwarding address by navigating to Settings > My Details > Setup Incoming and Outgoing Email > Incoming Email. When setting up this rule please ensure you tick the option to keep a copy of the email in your inbox.