For our VPS, MDH, OHP, and WebPro hosting accounts, use your domain name without a subdomain, as your outgoing SMTP server. This is in the format of "domain.com", not "smtp.domain.com".
For our Cobalt RAQ server hosting accounts (Standard, Pro, Ultra, E-Biz, Bridge, or Ultra) and our UPipe you must use your ISP's outgoing mail server.
Many Internet service providers (ISPs) will not allow you to use any SMTP server except for their own. In this case, you would need to use your ISP's mail server for outgoing email.