When I create a new virtual server in Virtualmin and assign it to a reseller, the welcome email is sent from the reseller's email address. This is a good idea, but with SPF and other anti-spam obstacles, this is now a more serious issue than previously. In fact, if a reseller has a Gmail address (gag), these messages don't even get put in their spam folder; they just disappear.
I should make an intelligent suggestion to improve this, but Virtualmin shouldn't be "impersonating" the reseller's email address. There must be a better way. Perhaps the return path can be a sub-domain directly under the control of the server admin.