I cannot tell you how long I have been using Yahoo mail but it is a long, long time. Today I was reading an email and noticed that Yahoo mail identified that the domain keys for the mail had been verified. It had a link to an explanation of domain keys so I followed it. I knew that my ISP blocked port 25 to other SMTP servers and if I could not get to Yahoo’s SMTP server then domain keys was not going to be very helpful. It was in the domain keys info I found that Yahoo had opened port 587 for authenticated SMTP traffic. Now that is cool!
So I changed my email account to support the new smtp port and not surprisingly it didn’t work. The error message said it could not find the server. That sounds like a firewall blocking access. Since Trend hadn’t popped up a message I was pretty sure ISA was blocking the port. My default configuration blocks anonymous access for most ports. So I created a protocol definition for port 587 and enabled it in my default rule. Now it works like a charm.