number in sender name

[Joe Acquisto-j4]

Using SpamAssassin 3.4.5 (2021-03-20)

Perhaps memory fails, but was there not, once, a standard rule that detected 
non alpha characters in 
sender name?  The domain/provider is not of interest for this question.

Such as this item (not the actual sender name)

        *  1.0 FREEMAIL_FROM Sender email is commonly abused enduser mail
        *      provider
        *      [abcd531if7[at]gmail.com]

Thanks.