To configure TextMarketer SMS for use with TERMS you need to ensure that TextMarketer will accept your SMS emails and enter the security details you were given by TextMarketer.
Go the Site Parameters within TERMS and select the SMS tab. Choose TexMarketer from the drop down and enter the security details you were given.
Within the TERMS email settings make a note of the "System from address"
Go into TextMarketer and go to the Account Settings
Then enter the domain from your "system from address" (westmarchsystems.co.uk in the example above) into the Use Domain Authentication of the Email Gateway Settings. Also ensure that the "Active" box is set.