RUCLS is currently experiencing an increased volume of blocked, rejected, or delayed mail due to spam and virus activity.  We are working to implement changes on our network, which will allow us to identify these sources of abuse.  In the interim, as well as long term, we ask all customers to ensure your PC’s are protected with up-to-date security software.
Make sure you're not spamming or infected!  Update and run your security software, which should include both antivirus and spam protection.  You can also download and run these free tools to help combat virus and spam problems (THESE FREE TOOLS ARE NOT INTENDED TO REPLACE YOUR SUBSCRIBED SECURITY SOFTWARE PACKAGE).

Ad-Aware
http://www.download.com/Ad-Aware-SE-Personal-Edition/3000-8022_4-10045910.html?part=dl-ad-aware&subj=dl&tag=top5

SpyBot
http://www.download.com/Spybot-Search-Destroy/3000-8022_4-10401314.html?tag=lst-0-1

Stinger
http://vil.nai.com/vil/stinger/polipstinger.asp