Is it possible to configure incoming email without Exchange?

We created a separate network for a customer that is behind a firewall. We do not have any Exchange server. The IT guy configured the outgoing email using some smtp relay service but he told us that this would only work for the outgoing email.  Is it possible to also configure the incoming email?  We have several document libraries that are configured to accept incoming emails.  I followed the instruction I found herehttps://technet.microsoft.com/en-us/library/cc287879.aspx

So I have the smtp service running.  I can see the smtp virtual server in IIS 6 (we also have IIS 7 but enabled IIS6 compatibility on it).  SharePoint is configured to allow incoming emails.  Under smtp in IIS, under Relay I have it set up to allow relay from all computers.  But, our document library is still not receiving any emails.  Is there anything else I need to do?

thanks,