Willcom, "Outbound Port 25 Blocking" implemented

In short, when sending mail for mobile phones, I will restrict e-mail transmission using port 25 that does not go through WILLCOM's mail server. There is no problem if it goes through Willcom 's mail server. Start from May 25th.

WILLCOM | Implementation of "Outbound Port 25 Blocking" for anti-spam measures for mobile phones
http://www.willcom-inc.com/ja/corporate/press/2006/04/14/index.html

In many providers, it is common to dynamically assign IP addresses, and senders of spam centered on dating, fraud, etc., can exploit this mechanism, making it difficult to identify senders of junk e-mail doing.
"Outbound Port 25 Blocking" regulates such transmission behavior. With this countermeasure, from WILLCOM'S Internet connection service (PRIN), directly to the mail server of the main mobile phone operator (NTT DoCoMo, au, TUKA group, Vodafone) without passing through WILLCOM 's mail server Mail with SMTP No. 25 We will prohibit acts to send.

In addition, it is not necessary to set up on the customer side, so if you are a customer using WILLCOM's mail service as usual it is possible to send e-mails to mobile phone operators as before.

I wonder if there is a problem only when I set up a mail server on my own and send it. Well Ordinarily it does not do such things and there should not be so many people sending unsolicited e-mail for mobile phones, so the impact will be minor for the public.