On Thu, 21 Nov 2019 at 12:05, Chris Green <c...@isbd.net> wrote: > I run postfix on an 'always on' machine at home and have the MX record > for my domain pointing at this machine. > > Obviously there are occasional downtimes, for example this morning we > had a 3 hour power failure and I also need to upgrade the machine > occasionally. > > Now I could of course overcome some of these down times (by using a > UPS etc.) but I have other priorities really so I think things are > likely to stay much as they are at present. > > So, if I set up a lower priority backup MX record pointing at a > virtual machine I run on a domain right away from my home machines > would I actually win anything much apart from yet another bit of admin > required? > > Sending systems will automatically back off and retry at intervals (I > have seen this happen when I have upgraded my home server in the past) > so will a secondary/backup MX actually help at all? > > > Another approach I might take is to have a backup machine here at home > with Postfix configured on it to take over if I know I'm doing an > upgrade on the main machine. All I would need to do to swap would be > to change the port forwarding destination on my router. Does anyone > here do something like this and are there any 'gotchas'? >
I use a VM in a different country with the same priority MX so that we should have effectively zero overall downtime. (The exceptions are when I propagate a broken configuration from one MTA to the other - oops.) There are some complications to this setup but I have it working neatly. However I have often heard it said here that such an approach is overkill. It is true that occasional downtimes may not be a big issue for incoming emails - they should be deferred and then resent by their MTAs when your MTA is back online. But if you (+others) need your MTA to send outgoing emails it may cause aggravation when it is down, especially as MUAs do not necessarily (or ever?) wait and retry.
