earthlink.net email receiving issues?

Hi!
Please remind us again how we fix the issue of customers who have "earthlink.net" email addresses that do not receive any emails from us? Just ran into the issue again....we have a customer who I can see has requested his password 3x and his profiles shows a send however he swears it's not in his inbox or is spam folder. I even sent him an email from directly within the console and he did not receive it either.....please advise what we should do?

If earthlink is blocking, the issue must be addressed with earthlink.

Your customer can contact earthlink for instructions to whitelist your emails.

Ok are you sure? Last time it was something Dave had to do with contacting earthlink?