What is it?
A Smart Host is simply a relay host that relays SMTP traffic from an SMTP server, mail client, or any other service or programming language capable of handling SMTP.
SoftLayer's Email Delivery Service
SoftLayer now offers an Email Delivery Service that allows clients to utilize a SmartHost to relay their outbound mail services. This is not “just a relay” as the service also generates metrics, tracks email lists, tracks email activity (bounced, clicked, dropped, opened, etc), assists with newsletters, provides authentication, and much more.
How it is configured and applied can vary depending on the OS, mail server, mail client, programming language, server management software, etc. Following the software developers’ and maintainers’ documentation is always advised, however, we have taken the time to provide some examples.