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This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.

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We have a really weird issue. &nbsp; We cannot receive emails from a domain that is using Postini filter services. &nbsp;It's telling them that their email was rejected because of an SPF check failed- on relay of Mail from &nbsp;&lt;somebody@theirdomain.com&gt;<wbr /> &nbsp;SMTP error code is 550. <br />
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We do not have an SPF record set up. &nbsp;According to Postini they do not check the SPF record. &nbsp;We can send to them just fine. &nbsp;We can receive email from 1 person there, and no one else. &nbsp;That's what's making this weird. &nbsp;I never see it hitting our Exchange 2003 server. &nbsp; We were talking about setting up an SPF record, but this is the only company we are having issues with. &nbsp;We both recently changed ISP's. &nbsp;They also recently got a new mail server.<br />
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What else should I check? &nbsp; How do I solve this issue?
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We have a really weird issue.   We cannot receive emails from a domain that is using Postini filter services.  It's telling them that their email was rejected because of an SPF check failed- on relay of Mail from  <somebody@theirdomain.com>  SMTP error code is 550. 

We do not have an SPF record set up.  According to Postini they do not check the SPF record.  We can send to them just fine.  We can receive email from 1 person there, and no one else.  That's what's making this weird.  I never see it hitting our Exchange 2003 server.   We were talking about setting up an SPF record, but this is the only company we are having issues with.  We both recently changed ISP's.  They also recently got a new mail server.

What else should I check?   How do I solve this issue?

Cannot receive emails from 1 domain that is using Postini filter services

A vulnerability is a weakness which allows an attacker to reduce a system's information assurance. Vulnerability is the intersection of three elements: a system susceptibility or flaw, attacker access to the flaw, and attacker capability to exploit the flaw. To exploit a vulnerability, an attacker must have at least one applicable tool or technique that can connect to a system weakness, known as the attack surface. Vulnerability management is the cyclical practice of identifying, classifying, remediating, and mitigating vulnerabilities. Other vulnerabilities include security risks, security defects and constructs in programming languages that are difficult to use properly.

Vulnerabilities

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.