Test SMTP Service in IIS and Exchange

How can I test to see if my SMTP service is ready to receive incoming mail?
There are a couple of ways to verify if the SMTP service is working properly:

Testing with an e-mail client

First, you can choose to use a standard Internet e-mail client program, such as Microsoft Outlook Express, for a quick verification. Locate the place where you can specify the outgoing e-mail (SMTP) server and change it to the domain name of the new SMTP server. Send a test message to your regular e-mail address and verify its delivery.

Note: There are many small e-mail clients made for the purpose of sending e-mail to mail servers without needing to configure them with e-mail accounts (like you need to do with Outlook Express for example). You can use any of these small (and mostly freeware) programs for fast troubleshooting.
You can also use a small tool that does not require installation:

• Ghost Mail 5.1

Testing with the Pickup directory

You can also compose a simple e-mail text file based on the SMTP specifications (RFC 822). Here is the content of a sample text file typed in Notepad:

From: myname@mydomain.com
To: someone@somedomain.com
Subject: testing
This is the test message body.

Simply copy or move the text file into the Pickup directory where SMTP was installed. (The default path should be “‘Inetpub’mailroot’Pickup” but if you have Exchange installed then the path will be “‘Program Files\Exchsrvr\Mailroot\Vsi 1\Pickup”.)
The SMTP service periodically checks into the Pickup directory and will attempt to deliver any of the messages found in the directory. Verify if you can receive the test message from the destination mailbox.
For more information about the RFC 822 specification for a properly formatted message, refer to The RFC 822 Message Format.
Testing with Telnet
You can also use TELNET to test your SMTP service. SMTP uses port number 25, so in order to use telnet to open an SMTP session with an Exchange server we use the command

​telnet srv1.dpetri.net 25

If the connection is successful, we should see a banner and a command line interface. We then need to follow RFC 821 for the accepted SMTP commands, which are quite simple (as the name says…)

​220 srv1.dpetri.net Microsoft ESMTP MAIL Service, Version: 5.0.2195.5329 ready at Sun, 15
Sep 2002 23:51:06 +0200
helo srv1.dpetri.net
250 srv1.dpetri.net Hello [192.168.0.100]
mail from: admin@petri.com
250 2.1.0 admin@petri.com....Sender OK
rcpt to: danielp@dpetri.net
250 2.1.5 danielp@dpetri.net
data
354 Start mail input; end with .
subject: this is a test
Hi Daniel
I'm trying to test this connection from Telnet.
Let me know if you get this message.
.
250 2.6.0  Queued mail for delivery
quit
221 2.0.0 srv1.dpetri.net Service closing transmission channel
Connection to host lost.
Press any key to continue...

(Screenshot of the same dialog)