Slow internal response, apache to postfix, 10.3.9 Server

I'm trying to send an email list internally from Apache, using PHP, to the SMTP server. The response is very slow. For one email it takes about a minute. It appears to slow down during the initial handshake between Apache and Postfix. Once an email is sent, a second one can be done instantly. What can I do to speed up the process/ Thanks Lee