[Zope] = replaced with == in sendmail!!!!!

I have the following inside a sendmail tag <!--#var URL1-->/completeReg?MagicNumber=<!--#var MagicNumber--> However in the mail that is sent this comes out as http://blah.com/completeReg?MagicNumber==23423434 This is incredibly fustrating and I can find no way around this. Even <!--#var URL1-->/completeReg?MagicNumber<!--#var "'='"--><!--#var MagicNumber--> produces the same result. Whats going on?