The company I work for use webmail so any employee can open a web browser and type https://mail.ournetwork/exchange and then log in.

Now this all works fine when 1 router is working but like today when Zen went down so does webmail.

I've checked on our firewall re. rules as to what uses which broadband line (we have 4 bb lines) but cannot see a rule set in there so I think it must be taking its routing from the exchange server somewhere?

Anyone have any thoughts where to look as I would like to re-route webmail to use the bb line that is currently working !

Can I clarify a couple of points?

When you say https://mail.ournetwork/exchange do you mean people internally accessing it or do you mean people externally accessing it?

If it's external, then look at the IP address which the A record for mail.ournetwork.tld points to on whoever hosts it for you.

If it's internal, then look at your DNS server.

Where I work, we use https://ourdomain.co.uk/owa for external access and //mailserver/owa for internal access.

Simple suggestion: ping mail.ournetwork and see what it resolves to.

Its external mail.

I did a ping test and it is pointing to 1 of the zen routers that are currently down.

Logged on to PlusNet as they host the domain and looked at the email settings and it had "mail" set to the zen router that is down so I assume all I need to do it edit this so "mail" is pointing to the PlusNet line that is up?

That will be a good start, but you'll also need to check the router on the PlusNet line has ports 80 and 443 forwarded to your mail server internal IP.

The 4 routers are managed by a Watchguard System Manager which reports that ports 80 and 443 arriving on the PlusNet line are forwarded to the exchange server so that looks good.

I just pinged the webmail again and it is still reporting the zen line although I know that can take several hours for this change to be spotted by dns servers.

Can you access webmail using the PlusNet IP address? If so, then it should work when the DNS finishes propagating.

Well well I did not know you could do that

Popped the IP address ie. https://123.45.67.08/exchange and managed to log in ok to my webmail box so all looks good

BT exchange page is now showing the problem as "recently cleared" although I find this dubious as none of the 3 zen lines/routers respond when I ping them - supposed to be off work Friday but me thinks I will have to pop in for 30mins or so and give the routers a restart/kick !

It is the DNS setting on the Internet routers (not your local DNS). If the router with the IP address regestered for your domain goes down, you need to change the DNS address on the Internet routers (takes up to 48 hours to filter through)...

The best way would be to set up a DnyDNS account and register it on one of the other IP addresses for the other lines, then give the users instructions, when the main address doesn't respond, they should try the DynDNS address.

Alternatively, if a second line is on the same BB provider, but different cable, you could switch the IP address over. If the different lines are from different providers, you won't be able to do that.

Why not setup additional A records (mail2, mail3 etc) going to the other routers then add them as MX records as well.
That way if any line goes down then mail will still flow.
You could then create a round robin address going to these A records for webmail

Funny you should mention that as that is exactly what I did so I made "mail" as the PlusNet account and then "mail2" and "mail3" using one of the other Zen lines.

All broadband lines seem to be working ok at the moment - no explanation from Zen as to whats going on though.