Powershell script not recognizing my function

I have a powershell script that parses a file and send an email if it detects a certain pattern. I have the email code setup inside a function, and it all works fine when I run it from the ISE, but I used PS2EXE to be able to run the script as a service but it does not recognize the function "email". my code looks similar to this

#Do things | 
foreach{
    email($_)
}

function email($text){
    #email $text
}

When I convert it to exe and run it I get this error:

The term 'email' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.