Google Apps MX for User Accounts, Custom Postfix for Sending only, same domain

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http://serverfault.com – I have a google apps business account which provides the use of gmail's mx servers. I would like to use this for users to send/receive email. However, I have a specific need to send bulk emails on a regular basis, and according to Google's Sending Limits, we can only send 2K emails a day using their mail server. I have a vps which has a static IP (and port 25 unblocked), which I can install and configure postfix. I would like to use this mail server to send mail so I am not limited to 2K a day. I am willing to purchase a SSL cert to ensure encrypted connections to the mail server, and from t (HowTos)