Event Invites look non-sensical

Event Invites look non-sensical

When I send Event invites (through my CRM), my boss doesn't get the clean pretty invite (attached: Event Invite), he instead gets an invite that is all nonsensical (attached: Zoho Event Invites).  I haven't received complaints from people in my CRM, but I don't always get responses, which tells me that maybe those who don't respond, aren't getting a clean invite.  Why is this? How can it be fixed?  He uses  Outlook 2003 SP3.