Outbound Port 25 Blocking (OP25B) Implementation
What it is
Outbound Port 25 Blocking (OP25B) is a measure to prevent the intentional or unintentional sending of bulk unsolicited email through an Internet provider's Outgoing email server. Although senders of bulk unsolicited email intentionally send the email from their own computer or via their own server, a virus infected computer may be sending out bulk unsolicited email without the user being aware of it.
Unsolicited bulk email sent from an Asahi Net Internet connection service is almost always never sent through Asahi Net's Outgoing mail server. Instead it is sent indirectly, through port 25 using a non-Asahi Net outgoing mail server. OP25B therefore restricts the sending of such unsolicited bulk email.
The merit of Outbound Port 25 Blocking
If a user's computer becomes infected with a virus or is accessed without authorization it is possible for unsolicited bulk email and the user's personal information to be sent from that computer. OP25B is therefore a way of preventing the unintentional sending of unsolicited bulk email and personal information.