Spam from nacha.org

Many of our clients have continued to receive spoofed spam emails from nacha.org 

This has been going on for days. nacha.org  is using SPF records, so in order to prevent these messages, you really should be using SPF filtering- something we recommend for all of our clients. 
If for any reason you don't want to use SPF filtering, you are more prone on receiving spam and spoofed messages. But in the short term, you can create a content filter to prevent these messages as long as you are not doing any business with or expecting any email from nacha.org  Keep in mind that you may not be aware of it, but some of your users may be expecting emails from them, depending on the size of your company. Any time you implement a content filter, our recommendation is to quarantine the messages and not blackhole/block them altogether.

Please contact us if you have any questions about this.