1. spam/ISP事情

port 25 を閉じるISPが増えて、末端のPCからのspamが減っている模様。-- ToshinoriMaeno 2010-07-24 10:41:55

Port 25 blocking: http://www.postcastserver.com/help/Port_25_Blocking.aspx 

This list contains some of the major ISPs that block port 25 on their servers:
 * AT&T (can be unblocked at the request)
 * MindSpring
 * BellSouth
 * MSN
 * CableOne
 * NetZero
 * Charter
 * People PC
 * Comcast ATTBI
 * Sprynet
 * Cox
 * Sympatico.ca
 * EarthLink
 * Verio
 * Flashnet
 * Verizon
 * MediaOne

http://kb.mediatemple.net/questions/897/ISP+Outgoing+SMTP+Server+Listing.