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FYI...<br />
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My Exchange SMTP Relay Access is set to allow all computer which successfully authenticate to relay
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FYI...

My Exchange SMTP Relay Access is set to allow all computer which successfully authenticate to relay

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I have enabled POP3 on my exchange server which works perfectly internally. &nbsp;I have opened the necessary port 110 on the Firewall and can telnet to port 110 from an external source. &nbsp;From the outside using Outlook I pass all tests and have a checkmark where my outgoing server requires authentication is located. &nbsp;I can pull down messages but can not send to an external domain. &nbsp;Any Help?
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I have enabled POP3 on my exchange server which works perfectly internally.  I have opened the necessary port 110 on the Firewall and can telnet to port 110 from an external source.  From the outside using Outlook I pass all tests and have a checkmark where my outgoing server requires authentication is located.  I can pull down messages but can not send to an external domain.  Any Help?

POP3 550 5.7.1 Error

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

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.