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We just moved to exchange 2010 and everytime one of our remote users sends emails they instantly get back "Your message did not reach some or all of the intended recipients.

  Subject:  test
  Sent: 8/30/2011 10:06 AM

The following recipient(s) cannot be reached:

  '' on 8/30/2011 10:06 AM
        Server error: '550 5.7.1 Unable to relay' "

They are setup with POP3 so they dont gain access to the shared calendar/recourses.

I had to set the port to SSL 995 to get incoming trafic to come in and they can send emails to the internal domain (over the net) but not to any other ISPs. I have enabled secure login so that it would require TLS.

I set microsoft outlook 2010 "my outgoing server (smtp) requires authentication" and used their domain login credentials but it just spits the password back.

Does anyone have any ideas?


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Just out of curiousity, I'm wondering why you don't just set them up using Outlook Anywhere or let them use OWA. You're still paying for the remote users to use an Exchange license if they access their mailbox through POP3, so why not get your money's worth out of it? – smassey Aug 30 '11 at 21:06
up vote 0 down vote accepted

They need to relay off of port 587 if they're not already - port 25 is only present on the Default Receive Connector, which doesn't allow client relay like you're trying to do. You can also check the settings of the Client Receive Connector to ensure it matches the settings you're trying to use.

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