Tuesday, 14 June 2011

Setting SMTP Banner In Exchange 2010…

All Exchange admins are familiar with the SMTP banner. It is the response received by a remote server after it connects to the receive connector of an Exchange 2010 Hub or Edge server. If the SMTP banner is not set on a receive connector, the default response will have the fqdn of the server, along with the information that the server in use is a Microsoft one.

Below is the default response from my telnet client. As the internal information becomes visible to outside servers, exchange admins tend to change it.

Default Telnet response 2010 SP1

I have seen companies using the “Specify the fqdn this connector will provide in response to EHLO” option in the receive connector as a means to set the banner. It is NOT the right way to do it.

Wrong way of setting smtp banner

The “banner” parameter of the Set-ReceiveConnector cmdlet needs to be used to configure the banner. Run the command below to set the banner. The banner text should start with 220, as stated in RFC 2821.

Set-ReceiveConnector –identity “Server\Connectorname” –Banner “220 banner text”

Set SMTP Banner

Once it is set, a telnet session will respond with the new banner.

Telnet Banner Response


6 comments:

Anonymous said...

I am interested to know why it is not s good idea to set it in the GUI. It seems MS made that for us....

Iraqi Dinar said...

I came onto your blog and focus just slightly submits. Nice strategy for text. I'll be bookmarking straight away seize all of your rss.

Rajith Jose Enchiparambil said...

Thanks Dinar

Rajith Jose Enchiparambil said...

Hi Anonymous,

You can't set a banner (except internal server name, null value etc) on the default receive connector. You will need to create a new receive connector and play with the IPs to make the connector unique, then apply your banner text.

Shell makes it easier, just a one-liner, no need of new connectors.

Michael Seidl said...

Hi Rajith,

but it is also recommended to create a separate Receive Connector, so there is no problem i think, to customize this Line in the GUI on the newly created Receive Connector.

Michael Seidl aka Techguy

Rajith Jose Enchiparambil said...

Hi Michael,

Nothing wrong with creating a new connector. By default, you don't have to and use the cmdlet to set the banner.

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