Email Server Blocks at various websites

Hello,

Apparently somone on my network has a email worm virus, and has got me on some ban lists.  I am trying to find the infected computer, but have not been able to yet, but I blocked access to port 25 from everyone in my network except the mail server.  

 I recieved this error when I tried to send out an email to a hotmail user.  
550 Command rejected for policy reasons. For troubleshooting information, go to http://postmaster.msn.com

How do I fix the issue to send out to hotmail users again?
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Tom_HickersonAsked:
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KyanarConnect With a Mentor Commented:
"Hotmail now have new policies on accepting mail from mail servers.

They will not accept mail from a mail server that does not have a  SPA record in their DNS.
Check that your DNS for your domain contains a TXT entry with SPA information."

This is not correct.  Hotmail will still accept email from any valid SMTP server, provided it has a reverse DNS entry.  SPF records are NOT required, but when in place will actually cause the Junk Mail filter to be less likely to consider your email as spam.

Reverse DNS entries are probably set up by your ISP, so it is unlikely to be that.  Also possible, is that a machine on your network attempted to open more than 500 simultaneous connections to a Hotmail server, which triggers a block.

Visit http://postmaster.msn.com/Troubleshooting.aspx for assistance, and an email you can contact to find out what you can do.
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kgreeneitConnect With a Mentor Commented:
hi there, you need to go to this website and enter the ip address of your mail server in the spam database checker to see if you are blacklisted. It should give you contact details of the blacklister and information on how to get yourself unlisted.

http://www.dnsstuff.com/

hope this helps!
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jimmymcp02Commented:
That happend to us but it was not a virus...we were sending mass emails and we forgot an unsuscribe link and we were banned from hotmail, yahoo and aol we had to comply with their policies. also it looks like something was wrong with our dns settings. also check that your exchange was not use for NDR spam
http://www.amset.info/exchange/spam-cleanup.asp
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Tony-FreemanCommented:
Hotmail now have new policies on accepting mail from mail servers.

They will not accept mail from a mail server that does not have a  SPA record in their DNS.
Check that your DNS for your domain contains a TXT entry with SPA information.
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Tom_HickersonAuthor Commented:
what is spa and do I do that with my registar?
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Tony-FreemanCommented:
sorry ... my typo .... I meant SPF.
This is a DNS entry for your domain name.

If your mail server was mail.yourdomain.com
then a typical entry would be
mail    TXT   v=spf1 mx ptr ?all
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Tom_HickersonAuthor Commented:
where do I add/edit this info at?
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neomage23Commented:
You would add it like this...

http://www.michaelbrumm.com/spfwindowsdns/

-neo
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