Vonage email notifications and Apple Mail client

Vonage provides a very nice feature in which, as soon as someone leaves a voice mail message, Vonage sends out an email notification to up to five different email addresses, in addition to sending a text message to a cell phone alerting you that someone has left you a voice message on your Vonage phone. Besides getting just a text-based email notification, you can also opt to have Vonage attach a .WAV file to the email it sends to those email accounts you list in your account settings page on the Vonage web site. I think this is a great feature, because I have my iPhone set up to receive the text message, and I also configured my email accounts to receive the email notifications together with the attached .WAV file, so I can listen to the recorded voice mail messages right on the iPhone, without having to dial in to a Vonage number, or go to the Vonage web site to listen to the voice mail via a computer.

While the Vonage email notifications with the attached .WAV files arrive just fine in my mac.com and my aol.com email accounts, those same email messages are NOT being sent to my the roadrunner.com email account provided by Time-Warner cable, my Internet Service Provider.

When I brought this matter up the tech support people at Vonage, they theorized that the roadunner server might be blocking receipt of the emails sent by the Vonage server. However, the problem does not seem to be related to roadrunner.com, because those email messages actually do reside on the roadrunner server. I can see them all right, but only if I use a browser and check my messages via their Web Mail application. For some mysterious reason, my Apple Mail client is NOT receiving those messages, and I have no clue why that would be so.

Does anybody know what is going on here? Shouldn't Apple Mail be able to retrieve all the messages on the roadruner server? What could prevent Apple Mail from being able to do that? And, is there anything I can do to make those email notifications —with their attached .WAV files—show up in my Inbox in Apple Mail?

Since I thankfully receiving those email notifications at my mac.com and my aol.com accounts, this is not a mission-critical issue for me. It is merely one of one technical curiosity.

bowlerboy