> - more and more ISP infrastructure practices OP25B for IPv4. OP25B = Outbound Port 25 Blocking. it disallows ISP customers to run SMTP server, or use SMTP server outside of the ISP network. maybe it is japanese-local acronym, google shows me japanese pages only. itojun _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf