It was the sending server (the one which generated the support emails from a web page) that needed the kick in the head, not the receiving server. The uktrainsim.com mail server itself hasn't been touched in months.
And an hour? Good heavens. I mean, a whole hour?

There can be a huge number of reasons for that, but basically it boils down to the fact that our server will try to contact your ISP immediately. If your ISP's server refuses to talk for whatever reason, our server will then re-try every hour. I won't be reconfiguring it to try any more often either otherwise it'll just die under a mound of retrying connections...
Steve