Sending email at same time cfmail

Make your code thread safe by wrapping it inside a cflock tag.  See the documentation here: http://help.adobe.com/en_US/ColdFusion/9.0/CFMLRef/WSc3ff6d0ea77859461172e0811cbec22c24-7f5d.html

Basically it will look something like this:

<cflock name="myEmailLock" type="exclusive" timeout="10">
      <cfmail>     
      ...
      </cfmail>
</cflock>

By wrapping your cfmail code with an exclusive lock like this only one user can run that code at any given time.  Note that this may introduce some timeout errors for other users trying to access this at the same time.  You will need to deal with that.  You may also want to include more code within the cflock tags depending on what you are doing.

Make sure that you are properly scoping your variables in your CFC.  Use the 'var' keyword when you create variables used inside your CFC functions, even query names.  Define all of your variables used inside the CFC immediately after any CFARGUMENT tags and before any other logic.  Something like this pseudo-code:

<cffunction name="myFunction" ...>

     <cfargument name="myArg1" ...>

     <cfargument name="myArg2" ...>

     <!--- Declare variables --->

     <cfset var myVar = "">

     <cfset var myQuery = "">

     <!--- Function logic --->

</cffunction>

HTH,

-Carl V.