Gavin said:

> I will have a look at greylisting, but I recall from when lug.org.uk
> implemented it that there was significant impact and delay with emails
> coming through and again this will lead to issues with clients calling
> me about emails that they were expecting.

Email is not a real-time service :)

With this implementation, the only one from any address that is delayed
for a few minutes is the first one. After that, they're in the accept
list and go straight through.

> An interesting thing I have just found from analysing todays logs is
> that almost all are being sent to email addresses (mostly rubbish names,
> e.g. message IDs) at a single client's domain name.  Is there a quick
> way in Exim to apply additional rules just to one domain (such as
> greylisting or strict application of RBLs)?

How large is the number of legit email addresses?