Thanks for that.
I shall leave it for the time being and not worry about it unless emails stop arriving.
Am I right to assume the "@" record is email related?
@ in DNS records means root, i.e. no sub-domain. They can be used on all types of records (I believe), including A and CNAME although having a @ CNAME record prevents all other @ records working (again, I believe)
Since no-ip have gone down because of Microsoft being cunts I actually got my subdomains working dynamic properly now.
Ended up using the free nameservers at afraid.org and pointing things through them.
That's how I do mine as well. And I use Tomato so the router actually notifies afraid.org when a change happens. Very set it and forget it and I like things like that!
5 min cronjob on one a local server is what I've been using.
I do something similar to afraid.org with Linode and their DNS Manager and PHP SDK. Useful if you already have hosting with them.