Mail Services and Backup MX/mail services

Question

I have a question regarding backup mail services and acceptance of incoming messages.
As of last week, I am new to the world of Mail Services in OS X Server 10.4. Last week, our current email server died and I was forced to take an Xserve G4 that had OS X Server 10.4.10 (unlimited) and setup mail services in order to receive and send mail. I went to a website called osx.topicdesk.com and followed their instructions for front-line spam defense and clamAV updating (and switching to clamd) which all appears to be working OK.
Because our old email server was having some hardware issues for the past several months that I had been working on, I had the feeling that failure might happen. So what I did a few months ago was sign up for Google Apps and their mail service. I added their MX records under my primary mail server so that in the case of a failure of my server, all mail would be passed to Gmail and everyone could get to their mail immediately (as any prolonged downtime won't work since this is a daily newspaper). This did work, for when my old server died, all the mail went immediately to the appropriate Google Apps mail accounts. After about a day of setup on the Xserve, I got the mail services running OK. I gave it all the same IP info as the previous server so that the mail would just start working without having to edit DNS records and such.
The problem I am having seems to be this: While I get most mail, some of my mail is still getting sent to the Google Apps accounts. For example, I have one user, Jane Doe, at [email protected] who gets most of their mail from connecting to the OS X Server, but about 2 - 3 emails a day get passed over to the Google Apps server. I have run DNSStuff.com tests on the mail connections, and I always get a good fast response out of the OS X server. My thinking was that mail would only be passed over to backup mail servers if the first server listed in the MX records was unavailable or offline. In all of my testing, my server has responded every time. The server is connecting via a gigabit network connection (good response), is a dual G4 1.33Ghz, 60GB hard drive with 2GB of RAM. This server doesn't do anything else except run Mail services (and web services for squirrelmail), it doesn't even have file sharing turned on.
My old email server was a Pentium II 400mhz with 348MB of RAM, and it caught all mail, so I know that the Xserve should be able to handle the load without being busy. Is there any reason that my Xserve would be rejecting mail and they would be siphoned off to the Google accounts?
Is this even a possible scenario to fix the problem: Setup a backup MX "queue" account somewhere with one of the BackupMX online services that will catch these stray emails and then send it back to the primary server? But then can be turned off quickly to allow mail to go to the Google Apps accounts if my server went down. In other words, the DNS record would show my primary as 1, the backup mx service as 2, the google servers as 3, 4, 5 and so on. Can Backup MX services be turned off quickly like that so that if my server is down and I need email to be accessed immediately then just "turn off" the service (without modifying the DNS since that will take too long to propogate) so that mail bounces over to Google immediately?
I guess my first troubleshooting attempt should be to figure out why my OS X Server is not accepting all mail.
Thanks in advance for any help and suggestions.
G

Answer 1

When I first started with the company about 2 years ago, they had a really old Linux box (about 10 years old) that was used to host email. It was horrible. It would run OK, but if it ever went down or had a hiccup, it was an all-day project trying to deal with it. Unfortunately, the company did not want to spend any money on a new server or software of course. The answer I got was "well, it's just email". Sure, but if email EVER goes down for more than 15 seconds, all of the employees go into seizures and scream that the place will have to shut down. I work for a daily newspaper, so everything is running 24/7.
Knowing that one day that box was going to just die, I looked into some backup MX services. As pterobyte had mentioned is that with a secondary MX, the problem is that no one can get their mail at all until the primary server comes back up. I knew if that server ever went down, I had nothing to take its place, so I would have to order something or get a server from another location to use. Being unfamiliar with OS X Mail Services, I knew it would take me awhile to try to setup all the users and such. All the while at the newspaper, they would be screaming bloody murder that they needed email working for news, ads coming in, etc. And when I say if it goes down for 10 minutes they start getting into fetal positions in the floor screaming, I'm not far off exaggerating. I figured I was going to need something in place for them to check email while I worked on the primary.
Back in September/October 2007, I discovered that Google hosted free mail services call Google Apps. With Google, I could setup "matching" accounts and would still be able to use my domain name. You just had to use Google's servers as the higher numbered MX records. Luckily, I set up in time for back in November, the Linux box finally died. When it did, all email successfully went to their counterparts on the Google's servers. I had everyone go to the special Google Apps login site and they were able to check their email fine. I ended up having to take a box from another site and then I had another copy of OS X Server 10.4, so I loaded it and successfully setup email (with lots of help from pterobyte's tutorials). They were on Google's systems for about 2 days.
After the disaster, I went around and setup IMAP accounts on everyone's Thunderbird clients so that if our email server went down, they just simply check that mailbox. The nice thing with the Google IMAP is that they automatically see if emails are hitting that inbox from within their client. Right now, it still remains that the 2 original companies that hit the Google accounts still do. The city government email and email from a sister newspaper. Everything else gets directed to the primary server. Although sometimes that doesn't even work, as tonight I am having to work on a problem involving the Clamd app acting up - taking up nearly 100% of the CPU which in turn caused all the mail to be hung up in the queue. So since the mail server didn't "reject" the mail and grabbed it, their gmail "backup" didn't get anything in it. It was taking me forever to figure out what was going on, so I almost just told them to unplug the network cable from the email server so that everything definitely would be forwarded to gmail.
My wish is that I had a secondary mail server in house to not even worry about it - or better yet, I wished I could just outsource the email administration itself to someone else (like webmail.us which is now MailSafe). That way for the most part, they wouldn't lose email. But of course, the company doesn't want to spend the money or invest. Just gripe when the older equipment we have won't support what they want to do with it.
But the story above explains why I did what I did with the Google's servers. I do appreciate everyone's help and input on this particular problem. I am going to look around at the DNS and talk to at least our sister newspaper to see if I can see how they have their DNS setup.
Thanks!
G