メールを送ったら、ちょうど２５時間後に下記のようなメッセージが返ってきました。
Hi. This is the qmail-send program at plum.freemail.ne.jp.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<[email protected]>:
Unable to switch to /home2/free/i/XXXX: access denied. (#4.3.0)
I'm not going to try again; this message has been in the queue too long.
どういうこと？教えてください。