You have a typo: "malhost" vs. "mailhost" in your xconfmanager line.
Otherwise Windchill doesn't care about which mail server you use -- as long as it supports SMTP and you configure Windchill to send mail its way.
[Yes, with newer releases one can handle "smpts" / TSL / SSL as well, so, yes, one can send mail via gmail or the like -- assuming your IT department isn't blocking gmail, which they probably are.]