I have a SBS 2008 server that is running Exchange 2007. It is still working well but, of course, is old and not capable of all the security fixes that should be used. I want to migrate to use mailcow instead of or in addition to Exchange. I have installed a mailcow server in Ubuntu in Promax on another server in the local network and have adjusted all the DNS servers but can’t get mailcow to pick up the correct DNS settings. It keeps showing the IP of the existing Exchange server rather than the IP of the new mailcow server. I’m able send out from that instance of mailcow but not able to receive. I think that the not receiving problem is related to the wrong DNS being picked up. I did set up the mailcow server with the same primary domain as the existing Exchange server. I may delete that instance and redo it to point the mailcow server to a different domain that is not controlled by the AD and Exchange server which might work one mail domain that is not in AD and only partially works in Exchange now but am not at all sure that would work for the mail domains that are in the existing AD and fully work on the existing Exchange server.
I have searched for assistance in migrating from Exchange to a non-exchange server and for adding a non-exchange server as a secondary mail server but have not found anything helpful yet. Everything keeps showing how to move to another Exchange server or how to move to Office365 or how to move from a non-Exchange server to Exchange.
Can anyone recommend any resources that might point me in the right direction? I would certainly appreciate any pointers or experience you can share. I know that my question is only peripherally about mailcow but was hoping that someone else might have already done this and could help.
Thanks in advance for any and all responses.

That sounds like it’s expected. If you haven’t edited your DNS zone file (which you should not do until you’re ready to cut over) the DNS records will show what’s currently live, which should be your Exchange server.

Running it as a secondary mail server will be more complex than replacing it because they’re two completely separate architectures.

What did you name your mailcow hostname? Try adding a subdomain (or a spare domain, if you have one) and point the MX records of that subdomain to your mailcow instance, you should be able to receive emails.

Once you test that, you’ll need to add the domain(s) to mailcow, add all your users, aliases (aka Distribution Lists) and then use the sync jobs to move the email across. Only then, you should move your MX on the production domain.

Have something to say?

Join the community by quickly registering to participate in this discussion. We'd like to see you joining our great moo-community!

I had edited my DNS zones. I think the problem was that the mailcow domain was the same as my Exchange domain and Exchange made it self primary so would not allow the other MX record to be selected. I’ll try redoing mailcow to make a different (spare) domain that I own to be the mailcow domain. Thanks for confirming my suspicions. I’ll post back when I’ve tested that.

Here is how I have it done, as smooth transition without the need of a downtime or the rush to do it in one maintenance window:

  • Create a helper mail domain (MX record can stay internal if you have a DNS server already)
  • Add the Exchange mail domain to mailcow, and then add the helper domain as alias domain.
  • In mailcow, define the exchange server as sender dependent transport map (make sure that it accepts mailcow)

Now you can do per mailbox:

  • set up a sync job and migrate calender and contacts via Caldav Synchronizer in Outlook (I posted here a document in german for the steps)
  • set up a unconditional forwarder in Exchange for the mailbox to the user@aliasdomain.com (so that Exchange users can communicate with mailcow users, and external mails get pushed through to mailcow.

After this phase of coexistence and migration, you need to:

  • remove the sync jobs
  • point the MX record to mailcow (do not forget about SPF etc)
  • remove the alias domain in mailcow (optional)

You can test it with a pilot user without breaking anything.

Its a long time ago and I couldnt find my runbook, so it might not be 100% correct.

Here the link to the german thread:
https://community.mailcow.email/d/3562-best-practise-umzug-von-exchange-nach-mailcow

Thank you both so much. Just knowing that there is a way to make this work is a huge help.
If possible I would like to do the migration the way @esackbauer described (over time rather than in one migration windows) as we have multiple domains and some pretty large mailboxes to migrate and we do use email a lot. I’ll get mailcow changed to be in the spare / helper domain and work from there. Looks like I will have to do some research on what is needed in the Exchange server to get it to accept mailcow as a sender dependent transport but knowing that is what to look for is a big help
I’ve read the link about the calendar and contact migration and the linked text documents (I don’t speak German but Google Translate REALLY helps.) and am sure that will be helpful when I get to that point.
Thank you again to both faisal and esackbauer for sharing your knowledge.

a month later

I know I’m over due on giving and update. I only have a limited time window each week to work on this and got pulled off on more urgent issues a couple of weeks. I’m working my way through getting the sender dependent transport set in mailcow where it will connect to Exchange and on getting Exchange set to accept forwarding to the mailcow server. Looks like this are both a SSL protocols mismatch issues and, I think some DNS issues that I still have to sort out. (I have to deal with split horizon DNS and some NAT stuff.) This is taking way longer than I’d like but am continuing to get closer. I’ll try to update again soon with hopefully better progress.
Thanks again to both of you for your help.

No one is typing