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Two examples of error message below...<br />
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nlpi091.prodigy.net #553 5.3.0 nlpi091 - m9MISBuE005317, DNSBL:521&lt; 63.166.65.132 &gt;_is_blocked.__For_informa<wbr />tion_see_<a href="http://att.net/blocks" rel="ugc">http://att.net/blocks</a> ##<br />
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ejf@intrinsic.net<br />
mhb-03-ord.mailhop.org #550 Relaying denied ##<br />
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We are getting the above error when sending email to a few email addresses. Any idea as to why this is happening. We just upgraded to Excahnge 2007 and did not have this problem on Exchange 2003.
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Two examples of error message below...

nlpi091.prodigy.net #553 5.3.0 nlpi091 - m9MISBuE005317, DNSBL:521< 63.166.65.132 >_is_blocked.__For_information_see_http://att.net/blocks ##


ejf@intrinsic.net
mhb-03-ord.mailhop.org #550 Relaying denied ##


We are getting the above error when sending email to a few email addresses. Any idea as to why this is happening. We just upgraded to Excahnge 2007 and did not have this problem on Exchange 2003.

Exchange 2007 NDR

Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.

Email Protocols

Software is any set of instructions that directs a computer to perform specific tasks or operations. Computer software consists of programs, libraries and related non-executable data (such as documentation). Computer software is non-tangible, contrasted with computer hardware, which is the physical component of computers. Software written in a machine language is known as "machine code". However, in practice, software is usually written in high-level programming languages than machine language. High-level languages are translated into machine language using a compiler or interpreter or a combination of the two.

Software

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.