" 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?
pch.net publishes a SPF record: "v=spf1 ip4:204.61.210.70/32 mx mx:woodynet.net a:sprockets.gibbard.org a:ghosthacked.net ~all" Besides going from soft-fail (~all) to fail (-all), they are already giving you the tools you need to validate a MAIL FROM: claim. Rubens