Recently I had a couple of clients tell me that they were no longer getting the e-mails I have been sending from our only MLS system. This came as a shock to me because I set myself up as a cc for all my clients and I have been getting them without a hitch. The issue seems to be that Yahoo has black listed our MLS vendor the e-mails aren't making it to our clients with Yahoo e-mail addresses. This is a challenge that can be overcome with some creative thinking.
When you have clients set up on MLS automated listing searches you can cc yourself so that you get the same message that is being sent to your client. Once the message gets to you it is easy to forward the cc e-mail copy to the clients that have Yahoo address. Another tip is to change the subject line because in many cases when an automated e-mail is black listed they block repetitive subject lines so give this a try. It worked for us and maybe it can work for you also.