Can I have both Google Apps and another e-mail service in my MX records?

Question

I have a client who I'm switching to Google Apps. We've set up the Google Apps account but have not yet added Google's MX records. We're going to wait a few weeks before actually switching them over to Google Apps for mail.

In the meanwhile, Google won't actually activate the e-mail component of Google Apps until it can see the MX records in the DNS zone file. Can I keep the current MX records like they are, at a high priority (0,10,20,30) and then add the google apps MX records at a lower priority (110,120,130,140...) so that Google will verify but not actually start receiving mail, or will this cause problems? I'm assuming that it won't since the records are prioritized as long as the primary e-mail host stays online and available and does not get overloaded with e-mails.

Answer 1

This is dangerous. If your primary servers are unavailable - even for just a moment, and for any reason - google's servers will be contacted. If they return a 'permanent failure' error, the mail will bounce. If, however, you know that google's mail servers will return a 'temporary failure' (4xx) error, then you should be okay.