Regex test not working

[ruralheart]

Is there a specific version of regex for email custom filters.  I set block sender contains word or phrase /[3-9]/g then check the use regex box.  Test against a jumble of letters and numbers eg

5oiu4oijhgjg3 and test finds no result. Any ideas what I'm doing wrong?

I'm getting lots of emails where the sender address is a random jumble of letters and numbers. Here's an example tNd7RvnNzetPhvYaD6@tNd7RvnNzetPhvYaD6.com. The McAfee spam filter doesn't recognise them as spam (don't know why) so I was looking to block the email if there are one or more numbers in the sender's address.

Or should the question be: why isn't anti-spam blocking these emails?

Versions: McAfee Anti-Spam 17.3 Build 17.3.159 Last update 20/09/2017 Content version 6120 Content update 27/09/2017 11:25