Qmail doesn't use any of sendmail's files, so the below makes no sense. If the mail resolving problem is that the correct domain name isn't displayed in outgoing mail, do the following. Note that example.com is in this case your isp's domain name, replace accordingly. Open /var/qmail/control/defaultdomain in your favorite editor, and put in your domain name. So for example, in this case, /var/qmail/control/defaultdomain would in this case contain the line example.com . Next, do the same thing with the /var/qmail/control/defaulthost file. In fact, defaultdomain and defaulthost should be identical in your case. Then restart qmail. If you're running qmail the old fashioned not recommended way via csh -cf '/var/qmail/rc &' , then do telinit 1 to get into single user mode, login, and do telinit 3 to get back into multiuser mode. If you're running qmail via daemon tools, look at the docs for it to see how to restart qmail. Hth. Greg