Well it seems that slowly but surely ISPs are blocking port 25 (SMTP). I’m not sure if this is a good or a bad thing, theoretically it reduces zombie spam machines effectiveness but then it just makes life that much more difficult for anyone using SMTP. I know that for a while that SBC has been blocking SMTP, and they didnt bother to let anyone know. (I wrote about it last August). Now I looked a little more and it appears a number of the other large ISP’s are also doing it. Hard Hat Hosting (who they are, I dont know) has a useful article about which ISPs block port 25. Also Pod cast server has an article of intrest, though some of their suggestions are a bit silly (like switching ISPs. I dont know about the rest of you, but in my area my choices for broadbands are SBC and SBC and SBC).
For thoes that have port 25 blocked and cant unblock it (which SBC does do by request), ask your mail provider for an alternate SMTP port. Most offer it (587 is the normal alternate). If worse comes to worse, use Gmail. You can get pop access, and they even have a page about how to set up your pop acccess when port 25 is blocked.