We have a subscription-based web app that, once a client launches, sends an invitation to each of the client's users to join. One issue we are having relates to users of Earthlink in particular - we monitor the reply-to email account on these invitations, and see a large number of the generic:
I apologize for this automatic reply to your email.
To control spam, I now allow incoming messages only from senders I have approved beforehand.
If you would like to be added to my list of approved senders, please fill out the short request form (see link below). Once I approve you, I will receive your original message in my inbox. You do not need to resend your message. I apologize for this one-time inconvenience.
Click the link below to fill out the request
We'd obviously like to ensure delivery to these users, but don't want to have to go in and manually request access as an approved sender. I am sure the TL;DR solution to this is that there is nothing we can do, which we cna live with, but I wondered how others handle this situation, whether via a technical solution or otherwise.
I guess you could detect Earthlink email addresses when the user submits the form and show an iframe where the user fills in the Earthlink form themselves. Not a perfect solution by any means (primarily because not all Earthlink users will have this filtering enabled) but probably as good as it gets. Of course this solution relies on knowing the correct URL for the form which may not be possible if the form URL includes some kind of session key or account ID that's only provided in the auto-reply.
EDIT: Had a look at the Earthlink site and it seems the user must be logged-in to WebMail to access the form. Best you'll probably get is to drop them on the Earthlink Webmail Login Form with clear instructions on how to whitelist your domain (found here).