KB Issue
When setting up your IMail Server, the SMTP Banner must be the same as your Primary Fully Qualified Domain Name (FQDN).
Issue Details
Using the MxToolBox tools to run test against your mail server, you might run into problems if you do not have your Mail Server properly configured. As demonstrated below.
Warning - Reverse DNS matches SMTP Banner
Recreate Issue
When you first install your Mail Server, leave everything default, and then use the MxToolBox tools« to run tests against your domain that you have created mail for within IMail Server. You should get the message describes in this KB Article.
Resolve Issue
  1. Open the [IMail Administrator]
  2. Expand [Localhost]
  3. Expand [Services]
  4. Click on [SMTP]
  5. Then click on the [Advanced] Tab.
  6. Click [OK] on the warning dialog
  7. In the [Hello Message]
  8. Type the FQDN i.e. mail.domain.com or domain.com
    9. Depending on how you have your domain set up inside of IMail Server.
  9. Next, click on the [SMTP] tab
  10. Click [Stop], then wait for the system to stop SMTP Services.
  11. Next, click [Start] to restart the SMTP Service.
Once you have completed the above, go to [url:mxtoolbox.com|MxToolBox tools]
And type in your domain: mail.domain.com
And run the test, this is