We have two main offices - one in the US and one in the UK. Both have datacentres of equal size. Our domain is company.com and at the moment, the MX record points to an SMTP Gateway in the US. This is obviously a single point of failure, not just in terms of there being one gateway, but also if we lost the US datacentre.
The SMTP Gateway itself runs Trend, we use Exchange 2007 for our internal mail routing.
We are planning to build more SMTP Gateways so that we have two in the US and two in London.
What we'd like -
i. External inbound mail from Europe is sent to the UK Gateways
ii. External inbound mail from US and Asia is sent to the US Gateways
iii. If we lose either UK or US, then all mail is sent to the remaining datacentre
iv. Within each datacentre, inbound mail is split evenly between the two Gateways.
Does anyone know how to achieve this using MX records and costs etc?