Can I use Google Apps for domain Email and still use a "sendmail" server to send emails?

Question

I am using Google Apps for domain to host the email from my domain and I've setup the MX records on my site according to the Google documentation. Can I also use a "sendmail" server to send additional emails from my webserver without there being a conflict with Google APPS?

Specific questions: 1) I want to add MX records for my sendmail server to my webhost to avoid getting mail sent from my sendmail server marked as SPAM (via an IP lookup.) Will the MX records for Google Apps and my sendmail server conflict in any way? 2) Will Google Apps email still work correctly if I have a seperate sendmail server operating? I want Google Apps email to receive all of my emails, and only want to send extra mail from my sendmail server.

The main reason I want to have my own sendmail server is to have no limits on the number of emails I send out (currently my Google Apps email limits me to 250 sent emails a day per email account.)

If there is anyone out there who has done exactly this, please speak up!

Answer 1

MX records only affect receiving mail. Off-site servers trying to send email to your domain use MX records to determine which host(s) to send the mail to. You can set up a sendmail host to send mail without it having any effect at all on your MX records or your receiving mail. (SPF records do affect sending mail; if you use SPF, then you'll need to update it to list both your Google Apps hosts and your sendmail hosts.)

EDIT: Since your sendmail host is only for sending mail, it should not be listed as an MX record. Listing it as an MX record has several disadvantages:

• It may receive mail that's intended for your Google Apps host. (Even if you give it a lower priority, it may receive mail if your Google Apps host is down, or if there's an intermittent DNS or network failure, or...)
• It will receive spam, so you'll have to set up spam filters on the sendmail host, or you'll have to reconfigure your Google Apps spam filters to trust the sendmail host (otherwise they won't recognize the real sender of the spam).
• If you block SMTP to your sendmail host, to avoid the first two problems, then you may be penalized by spam filters (as jasonrm mentioned), and you may delay the delivery of legitimate email (if someone tries to email your sendmail host for whatever reason and is blocked).

Not listing a sendmail host in your MX records may cause some spam filters to slightly penalize you, as Zoredache mentioned, but setting up SPF instead should avoid this. (Any well-designed spam filters will honor SPF over MX records.)

If your sendmail host will be sending any email to your own users, you'll also need to make sure to configure it to relay email for your users to your Google Apps host.