Sometime ago I added a modification to the Copy+ forums that would notify the administrator when a new post was added (allowing him to quickly remove any spam, as well as respond quickly to genuine questions).
However, after some security upgrades by the site host, all emails seemed to stop working. This was because it wouldn’t allow mails to come from email addresses that didn’t belong to the domain – as this domain didn’t come with any email capability, this was therefore a bit of an issue. The solution was to use SMTP instead.
In time, though, we realised that the new post mod didn’t use SMTP. So, the other day, I found another mod which works in a similiar way, but uses SMTP. This has fixed the problem nicely.