My ISP has confirmed that the whole email system slowed down (to all practical intents and purposes read collapsed) due to a massive attack of infected emails that were received within a very short period of time. The messages were not lost (so I'm told), but queued. Today, things seem to be working again, and I am receiving mails from the last 3-4 days. I hope to catch up with everything by tomorrow. Apparently this was a general problem that has affected a good number of Internet Service Providers in Spain. This only comes to show how relatively easy it is to disrupt the normal operation of a basic Internet service as a result of the general spread of a malicious virus (big sigh...)