<cfmail to="me@mydomain.com" from="you@yourdomain.com" subject="Subject" type="html">
   <cfmailparam file="http://myfilelocation/pdfFile.pdf">
   Body of the email
</cfmail>

<cfmail to="me@mydomain.com" from="you@yourdomain.com" subject="Subject" type="html">
<cfmailparam file="d:websitesmysiteresourcespdf1.pdf">
   Body of the email
</cfmail>

<cfset tempFile = getTempDirectory(getTempFile()) />
<cfhttp url="http://myfilelocation/pdfFile.pdf" method="get" file="#tempFile#"></cfhttp>

<cfmail to="me@mydomain.com" from="you@yourdomain.com" subject="Subject" type="html">
   <cfmailparam file="#tempFile#">
   Body of the email
</cfmail>

<cfhttp method="get" url="http://myfilelocation/pdfFile.pdf">
<!---conversion--->
<cfif IsSimpleValue(cfhttp.Filecontent)>
    <cfset content = cfhttp.Filecontent>
<cfelse>
    <cfset content = cfhttp.Filecontent.toByteArray()>
</cfif>

<cfmailparam file="#fileNameOfYourChoice#" type="#cfhttp.Mimetype#" content="#content#" />