XFOR: Difference Between SMTP:* and SMTP: Address Space

SUMMARY

It is possible to configure the Address Space in an Internet Mail Connector (IMC), or Internet Mail Service in Exchange Server 5.0 or higher, with a specific domain the IMC will accept messages for, an asterisk (*), or blank space (entered with a single space bar entry). This article discusses the differences between the asterik and blank space entries.

When you use the Microsoft Exchange Internet Mail Connector (IMC) and you have two routes (address spaces), one with SMTP: and one with SMTP:*, mail will move on the SMTP:* route even if the cost for this route is higher than the SMTP: route.

Routing returns four values in order of "best fit" as follows:

• Exact match
  
  
• Wildcard match
  
  
• Partial substring match
  
  
• No match

SMTP:* is considered a wildcard match and SMTP: is considered a partial substring match.