Got this bounceback from a known "good" e-mail address. Any suggestions?
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MDaemon Delivery Status Notification - http://www.altn.com/dsn/
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The attached message had PERMANENT fatal delivery errors.

After one or more unsuccessful delivery attempts the attached message has
been removed from the MDaemon mail queue on this server. The number and
frequency of delivery attempts are determined by local configuration.

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YOUR MESSAGE WAS NOT DELIVERED TO ONE OR MORE RECIPIENTS
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Failed address: cdmass@hotmail.com

--- Session Transcript ---
Thu 2009-03-19 14:38:20: Parsing message
Thu 2009-03-19 14:38:20: * From: postmaster@classcreator.net
Thu 2009-03-19 14:38:20: * To: cdmass@hotmail.com
Thu 2009-03-19 14:38:20: * Subject: Riverside High School Class of '89 - 20th Reunion
Thu 2009-03-19 14:38:20: * Size (bytes): 4201
Thu 2009-03-19 14:38:20: * Message-ID: <1608116172.1200181237487867052.JavaMail.CCWEB3$@CCWEB3>
Thu 2009-03-19 14:38:20: Attempting SMTP connection to [hotmail.com]
Thu 2009-03-19 14:38:21: Resolving MX records for [hotmail.com] (DNS Server: 69.41.160....
Thu 2009-03-19 14:38:21: * P=005 S=000 D=hotmail.com TTL=(17) MX=[mx2.hotmail.com]
Thu 2009-03-19 14:38:21: * P=005 S=001 D=hotmail.com TTL=(17) MX=[mx3.hotmail.com]
Thu 2009-03-19 14:38:21: * P=005 S=002 D=hotmail.com TTL=(17) MX=[mx4.hotmail.com]
Thu 2009-03-19 14:38:21: * P=005 S=003 D=hotmail.com TTL=(17) MX=[mx1.hotmail.com]
Thu 2009-03-19 14:38:21: Attempting SMTP connection to [mx2.hotmail.com:25]
Thu 2009-03-19 14:38:21: Resolving A record for [mx2.hotmail.com] (DNS Server: 69.41.160....
Thu 2009-03-19 14:38:21: * D=mx2.hotmail.com TTL=(17) A=[65.55.92.136]
Thu 2009-03-19 14:38:21: Attempting SMTP connection to [65.55.92.136:25]
Thu 2009-03-19 14:38:21: Waiting for socket connection...
Thu 2009-03-19 14:38:21: * Connection established (69.41.172.242:4346 -> 65.55.92.136:25)
Thu 2009-03-19 14:38:21: Waiting for protocol to start...
Thu 2009-03-19 14:38:21: Socket connection closed by the other side (how rude!)
Thu 2009-03-19 14:38:21: * Winsock Error 10053 Connection abort.
Thu 2009-03-19 14:38:21: Connection closed
Thu 2009-03-19 14:38:21: Attempting SMTP connection to [mx3.hotmail.com:25]
Thu 2009-03-19 14:38:21: Resolving A record for [mx3.hotmail.com] (DNS Server: 69.41.160....
Thu 2009-03-19 14:38:21: * D=mx3.hotmail.com TTL=(17) A=[65.55.37.104]
Thu 2009-03-19 14:38:21: Attempting SMTP connection to [65.55.37.104:25]
Thu 2009-03-19 14:38:21: Waiting for socket connection...
Thu 2009-03-19 14:38:21: * Connection established (69.41.172.242:4357 -> 65.55.37.104:25)
Thu 2009-03-19 14:38:21: Waiting for protocol to start...
Thu 2009-03-19 14:38:21: <-- 220 col0-mc3-f36.Col0.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http://privacy.msn.com/Anti-spam/. Violations will result in use of equipment located in California and other states. Thu, 19 Mar 2009 11:38:21 -0700
Thu 2009-03-19 14:38:21: --> EHLO mail.classcreator.net
Thu 2009-03-19 14:38:21: <-- 250-col0-mc3-f36.Col0.hotmail.com (3.8.0.31) Hello [69.41.172.242]
Thu 2009-03-19 14:38:21: <-- 250-SIZE 29696000
Thu 2009-03-19 14:38:21: <-- 250-PIPELINING
Thu 2009-03-19 14:38:21: <-- 250-8bitmime
Thu 2009-03-19 14:38:21: <-- 250-BINARYMIME
Thu 2009-03-19 14:38:21: <-- 250-CHUNKING
Thu 2009-03-19 14:38:21: <-- 250-AUTH LOGIN
Thu 2009-03-19 14:38:21: <-- 250-AUTH=LOGIN
Thu 2009-03-19 14:38:21: <-- 250 OK
Thu 2009-03-19 14:38:21: --> MAIL From: SIZE=4201
Thu 2009-03-19 14:38:21: <-- 250 bounces@mail.classcreator.net....Sender OK
Thu 2009-03-19 14:38:21: --> RCPT To:
Thu 2009-03-19 14:38:21: <-- 550 Requested action not taken: mailbox unavailable
Thu 2009-03-19 14:38:21: --> QUIT
--- End Transcript ---

This message was delivered by MDaemon - http://www.altn.com/MDaemon/

Hi Eric,

Double check to make sure the spelling is accurate for the email address - if it is please verify that you are able to email this address outside of the system. According to their mail server this account does not exist in their system.

550 Requested action not taken: mailbox unavailable

This happened on my site and it was my own email addy!

I've been getting stuff since then, so it might have been a glitch, or hotmail being hotmail. Hard to say.

Hi Nancy,

The one for your account was from late February. There was a day or two there where we saw some short bounce notices come back from @live.com and @hotmail.com addresses even when the account was receiving the email. We forwarded them several examples and the notices stopped. If you haven't received any since then I wouldn't worry about it. I think it was just a temporary glitch on their system.