Answer

PROBLEM

Email fax requests fail with the following error: '451 4.4.0 primary target IP address responded with 421 4.2.1 unable to connect'

ENVIRONMENT

• GFI FaxMaker installed on a separate machine
• all supported environments

SOLUTION

• Open the Services console by clicking Start > Run > and typing 'services.msc'
• Locate the service Simple Mail Transfer Protocol (SMTP)
• Set the service to Automatic and start it

CAUSE

The Simple Mail Transfer Protocol service is not running and set to start manually