From what I understood from my searches, to avoid the "Access denied - Invalid HELO name (See RFC2821" when sending emails using the SMTP on a 2008 R2 server, its FQDN must be set and to enter it I do the following:

  1. Open IIS 6.0 Manager
  2. Click on the server name then right click on SMTP virtual server and select properties
  3. Click on Delivery tab then Advanced

At this point there is a text box that says "Fully qualified domain name". The server name is SERVER2 and the fixed i.p. is 206.xxx.xxx.5 What should I enter there ? I don't have a DNS to point to. I tried SERVER2.206.xxx.xxx.5 but when I clicked the "Check DNS" button it says it is invalid.


The FQDN that you enter in the field is the FQDN that your server will use to identify itself to other SMTP servers in the HELO/EHLO command. This FQDN should be a name that can be resolved to the public ip address that your server will use when making outbound SMTP connections. This FQDN does not need to match the actual computer name of the server and is completely unrelated to the actual computer name of the server and has absolutely no bearing on the operation of the server except in the aforementioned HELO/EHLO command.

So... if you want your server to identify itself to other SMTP servers as mail.example.com, then you would enter mail.example.com in the field. You would then create an A record in your public DNS for mail.example.com for the public ip address of the server and then have your ISP to create a PTR record in their DNS zone for the public ip address of the server for mail.example.com.

  • 1
    Followed the instructions. Worked perfectly! – Ben Junior Feb 1 at 22:25
  • Glad to help... – joeqwerty Feb 2 at 1:35

The Fully Qualified Domain Name (FQDN) is going to look like this:


If you don't know your domain name, you can find it by typing this at a command prompt:

wmic computername get domain

Let's say that the output from that command is:


Then your FQDN is:


You can also find the FQDN on the System Properties page. (It'll be called "Full computer name" there.) There are at least two ways to reach it.

  1. Right-click on the My Computer item on the desktop, and select Properties. Or,
  2. Windows Key+Break
  • The full computer name is SERVER2. There is no domain name or alias. We access the server (via RDC) by its ip address only. I typed "wmic server2 get domain" and it returned server2 - alias not found – Ben Junior Feb 1 at 2:18
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    It sounds like Server2 is not a member of a domain. In that case, I suppose the full computer name is just "Server2". I don't know if IIS/SMTP will like that. Perhaps someone with some IIS/SMTP-specific knowledge will be able to help. – Doug Deden Feb 1 at 4:16
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    In that wmic command, you need to run it on Server2. And use "computername" literally -- not substitute the actual server's name. – Doug Deden Feb 1 at 4:17
  • In my case, running the command in the server, from a RDC both "computername" and "server2" gave me the same response: "... - Alias not found" – Ben Junior Feb 1 at 14:09

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