I have ran into a problem that I think someone should have a really clever answer for.

Today we have our own mailserver that looks like "mail.domain.com" – which we use to send out mail to our customers (with a modified PHPMailer script). Usually around 5000 mails every day. Everything from customer support to invoices goes through there. The from-header is set to "[email protected]".

We are now thinking of migrating to Google Apps for internal use (with 70+ users). However, we cannot use Gmails SMTP for sending "bulk" mails (they have a limit of 500 outgoing mails per day) so we really want to keep using our current system for sending automated mail to our customers – and using gmails SMTP for our internal use.

So, how do we set up our SPF-records (Sender Policy Framework) for this? We do not want to get stuck in any filters for "spoofing" the sender from either type of account (the ones sent from our own server, and through Gmails).

In short: we want to be able to use the same e-mail adress (for sending) on two different SMTP servers (and therefore two different IP-adresses). Anyone with a good knowledge off SPF who knows how to go about? Or if it is even possible? Anything else I should think of when switching to Google Apps?