Merle,

 

I'm not entirely sure I understand what you're doing...are you setting the action for your event to send an email to more than one address -- the primary domain address as well as the alias.com address? Have you tried using a standard alias on the primary domain that includes the addresses you want to send to? E.g., Have the event action send an email to SMS_Text@primarydomain.com, which has both the user@primarydomain.com and user@alias.com addresses as part of it? 

so i have domain  abc.net, and an alias of xyz.com, and email address of ibi
so when I receive an email at ibi@abc.net, the even fires the event and  I  receive the text and everything is great.
When I receive an email at ibi@xyz,com,  it doesn't fire.
Also noticed the events don't let you do just an alias  either...but apparently, not a big desire by the SM base.. so just me :)