Is it really cluefull to have this paragraph? " Please make sure that your spam filters allow email from "pch.net" before you sign up, since we will need to automatically verify your email address. " Since we all know that whitelisting and blacklisting by in-band stated "from" email address is quite wrong-headed, from a clue standpoint. Perhaps something like this? " Please make sure that your spam filters allow email sent from <ip-addresses> with a from address of pch.net before you sign up, since we will need to automatically verify your email address. " Where <ip-addresses> is the output of a dig command against the outgoing smtp servers sending the notifications? In general, ML and other automated email things should have a way to display the bounce to the user, which would mean storing it for some small period of time. Otherwise it becomes rather difficult to do the right thing filtering wise. (Google seems to do this for their notifications that get 45x/55x) Joe