こっそりと。

メールが送れない。そのように言われてしまいました。
調べました。すると、barracuda.com の DNSBLに該当していることがわかりました。なぜ該当しているのかはよくわかりません。

http://mxtoolbox.com/ にアクセスし、該当のドメインを入力します。チャックをすると、数多くのサイトをチェックしてくれ、そのなかで、BARRACUDA に blacklist で該当していました。

すぐにhttp://www.barracudacentral.org/にアクセスし、Removal Requestを行いました。
しかし画像認証が見にくい！わかりにくい！10回ぐらい入れ直したよ・・

そして以下のようにメールがきました。翻訳しながら適当に読んでみてください。

Thank you for contacting Barracuda Networks regarding your issue. Your issue is important to us. We have assigned a confirmation number: BBRXXXXXXXXXX to this case.

We apologize for any inconvenience that this may have caused you. We have removed [IPアドレス] from our blocklist for 30 days, at which time it will be re-evaluated.

There are a number of reasons your IP address may have been listed as "poor", including:

1. The email server at this IP address contains a virus and has been sending out spam
2. The email server at this IP address may be configured incorrectly
3. The PC at this IP address may be infected with a virus or botnet software program
4. An individual in the organization at this IP address may have a PC infected with a virus or botnet program
5. This IP address may be a dynamic IP address which was previously utilized by a known spammer
6. The marketing department of a company at this IP address may be sending out bulk emails that do not comply with the CAN-SPAM Act
7. This IP address may have a insecure wireless network attached to it which could allow unknown users to use it's network connection to send out bulk email
8. In some rare cases, your recipients' Barracuda Spam Firewall may be misconfigured

If you do not think any of the above apply, please also contact the person who manages this IP address, as they may be better able to investigate this issue.

Thank you for your time and understanding.