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We have just finished setting up an Exchange 2010 server. So far I can send mail but not receive which I expect since we have not requested that the MX records be changed. My question is: Is there a way to test that inbound mail is set up correctly before I request that the MX records be changed to point to the Exchange 2010 server?



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Sure, use telnet!

The flow typically goes like this:

$ telnet <ip_address> 25
> helo
> mail
> rcpt
> data
> Mail Body here
> . <enter>

After that last step, you should get a message back from the SMTP server stating whether or not your mail was accepted. If it was, then look for it to land shortly in the user's mailbox.

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Careful of the relaying rules- you'll want the mail from: address to not be an internal one if you're trying this from outside your network. If you use an internal address, and it works, you may want to check to see if you're an open relay. – mfinni Jul 31 '13 at 21:19
@mfinni - good catch. – EEAA Jul 31 '13 at 21:20
To add the "official" MS article on this: – TheCleaner Jul 31 '13 at 21:36
AFAIK, Exchange doesn't and never has authenticated or validated the Sender address (in the Mail From command). If you can send email from ANY sender address to ANY external address via telnet without authenticating then you have an open relay. I just confirmed this by testing my Exchange 2010 server and supplying my "Exchange" email address in the Mail From command. Exchange rightfully told me that it was unable to relay for the external recipient. – joeqwerty Jul 31 '13 at 21:41
Yeah, I was giving a simple case. You describe the complete test for open relay. – mfinni Aug 1 '13 at 12:42

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