Office 365 is, in itself, not an expensive email hosting product. However, its costs can add up quickly as your company expands and/or you add service email accounts. Here is a way to save a few dollars on those special email accounts:
External Send-Only Email Option: (copier)
First, set up your free external service account email addresses. For example, I like to use http://www.gmx.com/ because it is free and you can use it for SMTP relaying. In this example I will set up an email address for my copier to send from:
domaincopierservice@gmx.com
This will avoid using an Office 365 account. I can then set up my copier to relay SMTP directly through GMX as shown below: