Need HELP: backup mailserver setup/usage
before I go any further I'd just like to point out that I would appreciate no non-sensical posts which will only add to the confusion. Please post only if you have done something similar and know exactly what I am talking about. I'd be happy to clarify any points if needed, just ask.
Ok, we run a Cpanel server. A few months back we had a few customers sign up for basic hosting plans who wanted to use THEIR OWN mailserver on their own systems (off-network).
They also wanted to use OUR mailserver as a backup mail server.
So this is what we did. We simply set up 2 MX records, the first one pointing to their mailserver's IP, using the hostname 'mail'
Secondary MX with a different hostname 'backup'.
Now, this has all been fine and dandy and working until a while ago when their own mailserver stopped working. The users who use their mailserver were getting bounced email messages.
Now my question is: HOW does one actually make use of backup mailserver for un-interrupted flow of mail?
From what I understand, when THEIR mailserver is DOWN the following happens:
1. any emails sent to their domain, are routed to our mailserver thanks to the secondary MX. However, since on our mailserver they have NOT set up all the same email accounts, the emails are simply dumped into the main account / catch-all email address. Correct / Wrong?
2. When their mailserver is down, and they try to SEND email - then it simply bounced back. How would the users use our email server?
From what I understand, they would have to create ALL the same email accounts (usernames) that they have on their own mailserver, on our server as well.
So when their mailserver is down, all the users would need to change the mailserver address to backup.thedomain.com and use the login information for their email accounts on our server.
Right ? / Wrong?
That's how I understood the current set up would work. Please correct me if I am wrong.
I would also very much appreciate any suggestions. tips how to make the backup mailserver more effective.
Is it really necessary to have the same email accounts set up on both servers, in case the primary is down? Seems logical to me that this would be the case ..
Is there any way to simply use the backup mailserver (our server) to HOLD their email and forward it to the main mailserver once it's back up and running?
I would very much appreciate any input on this. Please note the zone file records are set up correctly and no need to bring them into the discussion. The main issue here is how to 'use' the backup mailserver when the main one is down assuming the zone file records are all set up correctly.
Looking forward to some responses. Cheers
