andymac,
Yahoogroups was delaying email for about 4 hours when the latest crop of viruses came out, but for the last couple of weeks it has been coming though in 10 minutes or less.
Have you tried emailing your email account from your Freeserve account and from another email account that is not a Freeserve account to see how long it is taking to get to your email account.
Take Care,
Richard