Hmm it is a bit like y = x; y = x; // just in case Possible it ( the email software responsible ) has some sort of loop that adds the content-type and it 'forgets' ( read : programmer forgot ) to not display the content-type the second time round ( and the third , forth ... ). I havent done and programming for email software but a common is to use "var .= var2" ( or the equivalent in your langage of choice ) when "var = var2" was intended .. maybe