If you happen to see the following lines in your server logs every few minutes,

Jun 13 12:55:49 xserve1 postfix/tlsmgr[78539]: warning: no entropy source specified with parameter tls_random_source
Jun 13 12:55:49 xserve1 postfix/tlsmgr[78539]: warning: encryption keys etc. may be predictable

there is a fix.

Edit the /etc/postfix/main.cf with the following line:

    tls_random_source = dev:/dev/urandom

You might want to do a search for tls_random_source first just to make sure it isn't already specified.

After adding that line, save. Then run

	postfix reload

Watch the mail and system logs for a few minutes to make sure the error doesn't come back.